I can't get WiFi access point (AP) working on my RPi

Question

I want to control my Raspberry Pi 3B+ using VNC via the on-board WiFi. To this end, I am trying to set up a WiFi access point on wlan0. I followed the instructions at https://www.raspberrypi.org/documentation/configuration/wireless/access-point.md. I did not do the stuff in section "Using the Raspberry Pi as an access point to share an internet connection (bridge)" because I don't need to share the internet/network connection on eth0.

The problem I have is that I don't see the SSID of the access point on my computer or phone, so I can't connect to it.

Output of ifconfig (wlan0 part):

wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 192.168.4.1  netmask 255.255.255.0  broadcast 192.168.4.255
    inet6 fe80::d1f4:dcc8:df78:63c2  prefixlen 64  scopeid 0x20<link>
    ether b8:27:eb:6d:03:b4  txqueuelen 1000  (Ethernet)
    RX packets 0  bytes 0 (0.0 B)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 30  bytes 4714 (4.6 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

"sudo service hostapd status" says "active (running)".

"sudo service dnsmasq status" says "active (running)".

I set the WiFi country using raspi-config before applying the changes to the WiFi configuration for the access point. My /etc/wpa_supplicant/wpa_supplicant.conf file looks like this:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=CH

However, it's interesting to note that trying to modify the country setting with "sudo raspi-config" again, I now get an error saying "Could not communicate with wpa_supplicant".

Here's a copy of what dmesg says after booting the RPi:

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 4.14.79-v7+ (dc4@dc4-XPS13-9333) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1159 SMP Sun Nov 4 17:50:20 GMT 2018
[    0.000000] CPU: ARMv7 Processor [410fd034] revision 4 (ARMv7), cr=10c5383d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi 3 Model B Plus Rev 1.3
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] cma: Reserved 8 MiB at 0x3ac00000
[    0.000000] On node 0 totalpages: 242688
[    0.000000] free_area_init_node: node 0, pgdat 80c85280, node_mem_map ba39f000
[    0.000000]   Normal zone: 2133 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 242688 pages, LIFO batch:31
[    0.000000] percpu: Embedded 17 pages/cpu @ba348000 s38720 r8192 d22720 u69632
[    0.000000] pcpu-alloc: s38720 r8192 d22720 u69632 alloc=17*4096
[    0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3 
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 240555
[    0.000000] Kernel command line: 8250.nr_uarts=0 bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  dwc_otg.lpm_enable=0 console=ttyS0,115200 console=tty1 root=PARTUUID=ba33141e-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.000000] PID hash table entries: 4096 (order: 2, 16384 bytes)
[    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
[    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Memory: 940232K/970752K available (7168K kernel code, 576K rwdata, 2076K rodata, 1024K init, 698K bss, 22328K reserved, 8192K cma-reserved)
[    0.000000] Virtual kernel memory layout:
                   vector  : 0xffff0000 - 0xffff1000   (   4 kB)
                   fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
                   vmalloc : 0xbb800000 - 0xff800000   (1088 MB)
                   lowmem  : 0x80000000 - 0xbb400000   ( 948 MB)
                   modules : 0x7f000000 - 0x80000000   (  16 MB)
                     .text : 0x80008000 - 0x80800000   (8160 kB)
                     .init : 0x80b00000 - 0x80c00000   (1024 kB)
                     .data : 0x80c00000 - 0x80c9017c   ( 577 kB)
                      .bss : 0x80c97f04 - 0x80d468b0   ( 699 kB)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] ftrace: allocating 25287 entries in 75 pages
[    0.000000] Hierarchical RCU implementation.
[    0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[    0.000000] arch_timer: cp15 timer(s) running at 19.20MHz (phys).
[    0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
[    0.000007] sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
[    0.000019] Switching to timer-based delay loop, resolution 52ns
[    0.000266] Console: colour dummy device 80x30
[    0.000283] console [tty1] enabled
[    0.000307] Calibrating delay loop (skipped), value calculated using timer frequency.. 38.40 BogoMIPS (lpj=192000)
[    0.000322] pid_max: default: 32768 minimum: 301
[    0.000641] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000656] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.001596] Disabling memory control group subsystem
[    0.001674] CPU: Testing write buffer coherency: ok
[    0.002093] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.002496] Setting up static identity map for 0x100000 - 0x10003c
[    0.002616] Hierarchical SRCU implementation.
[    0.003290] smp: Bringing up secondary CPUs ...
[    0.004062] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[    0.004903] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
[    0.005722] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
[    0.005826] smp: Brought up 1 node, 4 CPUs
[    0.005836] SMP: Total of 4 processors activated (153.60 BogoMIPS).
[    0.005842] CPU: All CPU(s) started in HYP mode.
[    0.005846] CPU: Virtualization extensions available.
[    0.006769] devtmpfs: initialized
[    0.017023] random: get_random_u32 called from bucket_table_alloc+0xfc/0x24c with crng_init=0
[    0.017786] VFP support v0.3: implementor 41 architecture 3 part 40 variant 3 rev 4
[    0.018005] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.018023] futex hash table entries: 1024 (order: 4, 65536 bytes)
[    0.018578] pinctrl core: initialized pinctrl subsystem
[    0.019318] NET: Registered protocol family 16
[    0.022057] DMA: preallocated 1024 KiB pool for atomic coherent allocations
[    0.026935] hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
[    0.026943] hw-breakpoint: maximum watchpoint size is 8 bytes.
[    0.027140] Serial: AMBA PL011 UART driver
[    0.028807] bcm2835-mbox 3f00b880.mailbox: mailbox enabled
[    0.029263] uart-pl011 3f201000.serial: could not find pctldev for node /soc/gpio@7e200000/uart0_pins, deferring probe
[    0.060805] bcm2835-dma 3f007000.dma: DMA legacy API manager at bb813000, dmachans=0x1
[    0.062225] SCSI subsystem initialized
[    0.062450] usbcore: registered new interface driver usbfs
[    0.062501] usbcore: registered new interface driver hub
[    0.062586] usbcore: registered new device driver usb
[    0.070085] raspberrypi-firmware soc:firmware: Attached to firmware from 2018-11-04 16:31
[    0.071481] clocksource: Switched to clocksource arch_sys_counter
[    0.148395] VFS: Disk quotas dquot_6.6.0
[    0.148477] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[    0.148662] FS-Cache: Loaded
[    0.148845] CacheFiles: Loaded
[    0.156782] NET: Registered protocol family 2
[    0.157501] TCP established hash table entries: 8192 (order: 3, 32768 bytes)
[    0.157612] TCP bind hash table entries: 8192 (order: 4, 65536 bytes)
[    0.157797] TCP: Hash tables configured (established 8192 bind 8192)
[    0.157927] UDP hash table entries: 512 (order: 2, 16384 bytes)
[    0.157971] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes)
[    0.158201] NET: Registered protocol family 1
[    0.158670] RPC: Registered named UNIX socket transport module.
[    0.158676] RPC: Registered udp transport module.
[    0.158681] RPC: Registered tcp transport module.
[    0.158687] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.160338] hw perfevents: enabled with armv7_cortex_a7 PMU driver, 7 counters available
[    0.163080] workingset: timestamp_bits=14 max_order=18 bucket_order=4
[    0.170999] FS-Cache: Netfs 'nfs' registered for caching
[    0.171628] NFS: Registering the id_resolver key type
[    0.171663] Key type id_resolver registered
[    0.171669] Key type id_legacy registered
[    0.171684] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    0.173596] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[    0.173727] io scheduler noop registered
[    0.173734] io scheduler deadline registered (default)
[    0.173902] io scheduler cfq registered
[    0.173909] io scheduler mq-deadline registered
[    0.173915] io scheduler kyber registered
[    0.176213] BCM2708FB: allocated DMA memory fad00000
[    0.176239] BCM2708FB: allocated DMA channel 0 @ bb813000
[    0.184789] Console: switching to colour frame buffer device 82x26
[    0.190833] bcm2835-rng 3f104000.rng: hwrng registered
[    0.190961] vc-mem: phys_addr:0x00000000 mem_base=0x3ec00000 mem_size:0x40000000(1024 MiB)
[    0.191397] vc-sm: Videocore shared memory driver
[    0.191701] gpiomem-bcm2835 3f200000.gpiomem: Initialised: Registers at 0x3f200000
[    0.201119] brd: module loaded
[    0.209716] loop: module loaded
[    0.209729] Loading iSCSI transport class v2.0-870.
[    0.210379] libphy: Fixed MDIO Bus: probed
[    0.210475] usbcore: registered new interface driver lan78xx
[    0.210534] usbcore: registered new interface driver smsc95xx
[    0.210549] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[    0.236000] dwc_otg 3f980000.usb: base=0xf0980000
[    0.436191] Core Release: 2.80a
[    0.436200] Setting default values for core params
[    0.436231] Finished setting default values for core params
[    0.636478] Using Buffer DMA mode
[    0.636484] Periodic Transfer Interrupt Enhancement - disabled
[    0.636489] Multiprocessor Interrupt Enhancement - disabled
[    0.636496] OTG VER PARAM: 0, OTG VER FLAG: 0
[    0.636510] Dedicated Tx FIFOs mode
[    0.636896] WARN::dwc_otg_hcd_init:1046: FIQ DMA bounce buffers: virt = 0xbad14000 dma = 0xfad14000 len=9024
[    0.636921] FIQ FSM acceleration enabled for :
               Non-periodic Split Transactions
               Periodic Split Transactions
               High-Speed Isochronous Endpoints
               Interrupt/Control Split Transaction hack enabled
[    0.636928] dwc_otg: Microframe scheduler enabled
[    0.636975] WARN::hcd_init_fiq:459: FIQ on core 1 at 0x805ea470
[    0.636986] WARN::hcd_init_fiq:460: FIQ ASM at 0x805ea7d8 length 36
[    0.636998] WARN::hcd_init_fiq:486: MPHI regs_base at 0xf0006000
[    0.637048] dwc_otg 3f980000.usb: DWC OTG Controller
[    0.637078] dwc_otg 3f980000.usb: new USB bus registered, assigned bus number 1
[    0.637108] dwc_otg 3f980000.usb: irq 62, io mem 0x00000000
[    0.637156] Init: Port Power? op_state=1
[    0.637161] Init: Power Port (0)
[    0.637359] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[    0.637370] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    0.637379] usb usb1: Product: DWC OTG Controller
[    0.637387] usb usb1: Manufacturer: Linux 4.14.79-v7+ dwc_otg_hcd
[    0.637395] usb usb1: SerialNumber: 3f980000.usb
[    0.637997] hub 1-0:1.0: USB hub found
[    0.638036] hub 1-0:1.0: 1 port detected
[    0.638529] dwc_otg: FIQ enabled
[    0.638535] dwc_otg: NAK holdoff enabled
[    0.638539] dwc_otg: FIQ split-transaction FSM enabled
[    0.638550] Module dwc_common_port init
[    0.638766] usbcore: registered new interface driver usb-storage
[    0.638935] mousedev: PS/2 mouse device common for all mice
[    0.639003] IR NEC protocol handler initialized
[    0.639009] IR RC5(x/sz) protocol handler initialized
[    0.639014] IR RC6 protocol handler initialized
[    0.639019] IR JVC protocol handler initialized
[    0.639024] IR Sony protocol handler initialized
[    0.639029] IR SANYO protocol handler initialized
[    0.639034] IR Sharp protocol handler initialized
[    0.639039] IR MCE Keyboard/mouse protocol handler initialized
[    0.639044] IR XMP protocol handler initialized
[    0.639713] bcm2835-wdt 3f100000.watchdog: Broadcom BCM2835 watchdog timer
[    0.640622] bcm2835-cpufreq: min=600000 max=1400000
[    0.640974] sdhci: Secure Digital Host Controller Interface driver
[    0.640979] sdhci: Copyright(c) Pierre Ossman
[    0.641327] mmc-bcm2835 3f300000.mmc: could not get clk, deferring probe
[    0.641678] sdhost-bcm2835 3f202000.mmc: could not get clk, deferring probe
[    0.641770] sdhci-pltfm: SDHCI platform and OF driver helper
[    0.643182] ledtrig-cpu: registered to indicate activity on CPUs
[    0.643319] hidraw: raw HID events driver (C) Jiri Kosina
[    0.643498] usbcore: registered new interface driver usbhid
[    0.643502] usbhid: USB HID core driver
[    0.644101] vchiq: vchiq_init_state: slot_zero = bad80000, is_master = 0
[    0.645503] [vc_sm_connected_init]: start
[    0.654126] [vc_sm_connected_init]: end - returning 0
[    0.654691] Initializing XFRM netlink socket
[    0.654713] NET: Registered protocol family 17
[    0.654809] Key type dns_resolver registered
[    0.655338] Registering SWP/SWPB emulation handler
[    0.655909] registered taskstats version 1
[    0.661816] uart-pl011 3f201000.serial: cts_event_workaround enabled
[    0.661884] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 87, base_baud = 0) is a PL011 rev2
[    0.663667] mmc-bcm2835 3f300000.mmc: mmc_debug:0 mmc_debug2:0
[    0.663677] mmc-bcm2835 3f300000.mmc: DMA channel allocated
[    0.732088] sdhost: log_buf @ bad13000 (fad13000)
[    0.769801] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[    0.771369] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    0.772928] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    0.775710] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[    0.811502] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[    0.812494] of_cfs_init
[    0.812581] of_cfs_init: OK
[    0.813151] Waiting for root device PARTUUID=ba33141e-02...
[    0.851289] random: fast init done
[    0.859409] mmc1: new high speed SDIO card at address 0001
[    0.861586] Indeed it is in host mode hprt0 = 00021501
[    1.071562] usb 1-1: new high-speed USB device number 2 using dwc_otg
[    1.071701] Indeed it is in host mode hprt0 = 00001101
[    1.311755] usb 1-1: New USB device found, idVendor=0424, idProduct=2514
[    1.311767] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    1.312296] hub 1-1:1.0: USB hub found
[    1.312396] hub 1-1:1.0: 4 ports detected
[    1.631510] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[    1.761740] usb 1-1.1: New USB device found, idVendor=0424, idProduct=2514
[    1.761751] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    1.762222] hub 1-1.1:1.0: USB hub found
[    1.762311] hub 1-1.1:1.0: 3 ports detected
[    2.115342] dwc_otg_handle_wakeup_detected_intr lxstate = 2
[    2.591561] usb 1-1.1.1: new high-speed USB device number 4 using dwc_otg
[    2.721892] usb 1-1.1.1: New USB device found, idVendor=0424, idProduct=7800
[    2.721903] usb 1-1.1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[    2.891589] usb 1-1.2: new high-speed USB device number 5 using dwc_otg
[    2.989271] libphy: lan78xx-mdiobus: probed
[    3.023056] usb 1-1.2: New USB device found, idVendor=0850, idProduct=0003
[    3.023067] usb 1-1.2: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[    3.023076] usb 1-1.2: Product: X850 V3.0
[    3.023084] usb 1-1.2: Manufacturer: SupTronics
[    3.023092] usb 1-1.2: SerialNumber: 201901000131
[    3.023688] usb-storage 1-1.2:1.0: USB Mass Storage device detected
[    3.024210] scsi host0: usb-storage 1-1.2:1.0
[    4.072703] scsi 0:0:0:0: Direct-Access     KINGSTON  SUV500MS120G    0    PQ: 0 ANSI: 6
[    4.073974] sd 0:0:0:0: [sda] 234441648 512-byte logical blocks: (120 GB/112 GiB)
[    4.074387] sd 0:0:0:0: [sda] Write Protect is off
[    4.074398] sd 0:0:0:0: [sda] Mode Sense: 43 00 00 00
[    4.074804] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[    4.076834]  sda: sda1 sda2
[    4.078713] sd 0:0:0:0: [sda] Attached SCSI disk
[    4.108164] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null)
[    4.108220] VFS: Mounted root (ext4 filesystem) readonly on device 8:2.
[    4.108772] devtmpfs: mounted
[    4.112055] Freeing unused kernel memory: 1024K
[    4.417069] systemd[1]: System time before build time, advancing clock.
[    4.499446] NET: Registered protocol family 10
[    4.500620] Segment Routing with IPv6
[    4.507812] ip_tables: (C) 2000-2006 Netfilter Core Team
[    4.520519] random: systemd: uninitialized urandom read (16 bytes read)
[    4.525867] systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
[    4.526408] systemd[1]: Detected architecture arm.
[    4.527141] systemd[1]: Set hostname to <raspberrypi>.
[    4.557888] random: systemd: uninitialized urandom read (16 bytes read)
[    4.582594] random: systemd-cryptse: uninitialized urandom read (16 bytes read)
[    4.916919] systemd[1]: Listening on udev Kernel Socket.
[    4.917543] systemd[1]: Listening on Journal Socket.
[    4.933317] systemd[1]: Created slice User and Session Slice.
[    4.933913] systemd[1]: Created slice System Slice.
[    4.938587] systemd[1]: Starting Load Kernel Modules...
[    4.938789] systemd[1]: Reached target Slices.
[    4.939870] systemd[1]: Created slice system-systemd\x2dfsck.slice.
[    5.027999] i2c /dev entries driver
[    5.225071] random: crng init done
[    5.225086] random: 7 urandom warning(s) missed due to ratelimiting
[    5.632698] EXT4-fs (sda2): re-mounted. Opts: (null)
[    5.706877] systemd-journald[99]: Received request to flush runtime journal from PID 1
[    6.189844] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.
[    6.200635] bcm2835_alsa bcm2835_alsa: card created with 8 channels
[    6.241849] brcmfmac: F1 signature read @0x18000000=0x15264345
[    6.252861] brcmfmac: brcmf_fw_map_chip_to_name: using brcm/brcmfmac43455-sdio.bin for chip 0x004345(17221) rev 0x000006
[    6.253345] usbcore: registered new interface driver brcmfmac
[    6.404106] sd 0:0:0:0: Attached scsi generic sg0 type 0
[    6.537693] brcmfmac: brcmf_c_preinit_dcmds: Firmware version = wl0: Feb 27 2018 03:15:32 version 7.45.154 (r684107 CY) FWID 01-4fbe0b04
[    6.538320] brcmfmac: brcmf_c_preinit_dcmds: CLM version = API: 12.2 Data: 9.10.105 Compiler: 1.29.4 ClmImport: 1.36.3 Creation: 2018-03-09 18:56:28 
[    7.944757] uart-pl011 3f201000.serial: no DMA platform data
[    8.178117] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[    8.214385] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[    8.214403] brcmfmac: power management disabled
[    8.448748] Adding 102396k swap on /var/swap.  Priority:-2 extents:1 across:102396k FS
[    8.594235] nf_conntrack version 0.5.0 (15360 buckets, 61440 max)
[    8.931738] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   12.424680] fuse init (API version 7.26)
[   14.497679] Bluetooth: Core ver 2.22
[   14.497738] NET: Registered protocol family 31
[   14.497741] Bluetooth: HCI device and connection manager initialized
[   14.497756] Bluetooth: HCI socket layer initialized
[   14.497763] Bluetooth: L2CAP socket layer initialized
[   14.497783] Bluetooth: SCO socket layer initialized
[   14.511961] Bluetooth: HCI UART driver ver 2.3
[   14.511973] Bluetooth: HCI UART protocol H4 registered
[   14.511976] Bluetooth: HCI UART protocol Three-wire (H5) registered
[   14.512165] Bluetooth: HCI UART protocol Broadcom registered
[   14.795736] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   14.795742] Bluetooth: BNEP filters: protocol multicast
[   14.795753] Bluetooth: BNEP socket layer initialized
[   14.837657] Bluetooth: RFCOMM TTY layer initialized
[   14.837676] Bluetooth: RFCOMM socket layer initialized
[   14.837693] Bluetooth: RFCOMM ver 1.11
[   16.110558] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

Output of "iw dev wlan0 info":

Interface wlan0
ifindex 3
wdev 0x1
addr b8:27:eb:6d:03:b4
ssid xyzruedi
type AP
wiphy 0
channel 7 (2442 MHz), width: 20 MHz, center1: 2442 MHz
txpower 31.00 dBm

Here is my /etc/hostapd/hostapd.conf file (with a bogus password):

interface=wlan0
driver=nl80211
ssid=xyzruedi
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=thisisabigsecret
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Edit 31 March 2019: In an earlier question I described how the access point does not (seem to) work if I boot the RPi3B+ from an SSD on the USB, whereas it does (seem to) work if booting from an SD card (see WiFi does not work if booting Raspberry Pi from SSD on USB). As this issue was a bit erratic, I thought the issue was not related to booting from USB vs SD card slot. However, I made another test by cloning the SSD to an SD card, and booting from the SD card. The access point worked ok on the RPi3B+ with the SD card! I also have an earlier RPi3B (not "plus"), which I used for testing: the access point works fine with the RPi3B no matter if I boot it from SD or USB. This seems to indicate the issue is specific to the RPi3B+. Any ideas what this could be?

How can I debug this? Any suggestions what to do?

Answer 1

As shown with iw dev wlan0 info the access point (type AP) is running on the RasPi with SSID xyzruedi using channel 7 in the 2,4 GHz band. So you should be able to connect to it. With the information so far I cannot see a reason why xyzruedi is not visible in the list of available networks you can connect to on your phone. Double check it. Maybe WiFi is disabled on the phone?

If you run a linux operating system on the laptop you should configure /etc/wpa_wpasupplicant/wpa_supplicant.conf with

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=CH

network={
    ssid="xyzruedi"
    psk="PasswordOfAccessPoint"
}

Then start wpa_supplicant and you should be connected. Check with

laptop ~$ sudo iw dev wlan0 link

Your hostapd.conf has an entry wmm_enabled=0 that isn't default 1. Look at zcat /usr/share/doc/hostapd/examples/hostapd.conf.gz | less. Here is my /etc/hostapd/hostapd.conf that I always use with success:

nterface=wlan0
driver=nl80211
ssid=RPiNet
country_code=DE
hw_mode=g
channel=1
auth_algs=1
wpa=2
wpa_passphrase=verySecretPassword
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

With wpa=2 keys are set to only use RSN(WPA2). You can try to set it to only use older WPA with wpa=1 or to use both with wpa=3.

For troubleshooting you can start hostapd manual in debug mode with:

rpi ~$ sudo /usr/sbin/hostapd -d -P /run/hostapd.pid /etc/hostapd/hostapd.conf

You may improve debug messages with -dd -K -t (see man hostapd).

You may have a look at some overlays of frequencies/channels or issues with 2,4GHz vs. 5GHz band, or something like this; or at Key negotiation, RSN(WPA2) vs. WPA.

If this all does not help you may consider to avoid using hostapd and instead using wpa_supplicant to configure an access point. How to it you can look at Setting up a Raspberry Pi as an access point - the easy way and follow section Setting up a stand alone access point.

Answer 2

I encountered the same problem:

RPi3B and Geekworm X850 mSATA SSD Extension Board V 3.1 an a Sunbow mSATA 32GB: Everything works as expected.

RPi3B+ and Geekworm X850 mSATA SSD Extension Board V 3.1 an a Sunbow mSATA 32GB: No Wifi regardless of the booting device (SD or SSD) unless the SSD has no power connection (via USB or external). Powering up the extension board results in no more Wifi!

Call me crazy, but the solution was: Don't use the metal-standoffs for mounting the extension board under the RPi3B+ ! Use plastic-standoffs or put the extension board beside the RPi3B+ using an USB-cable. There seems to be some EMI-problem between wifi chip and extension board (or SSD).

Cheers

b

Answer 3

I connected the USB drive to another RPi3B+, with no other changes to the setup. The WiFi worked out of the box as it should. I'd tend to say that my first RPi3B+ has a hardware issue.

Answer 4

"pi-ap" automates configuration of your Pi into a wireless AP. You can use the "pi-ap" scripts which are tested and proven to produce a working Pi wireless Access Point for comparative analysis with your own (broken) config. They're just a pile of bash scripts called in turn by the install.sh script. Things not obvious are well commented:

https://github.com/f1linux/pi-ap

Or, if you don't care about how things are breaking and just want to quickly produce a working wireless AP, just clone the repo into your Pi, change a few default variable values and then sudo ./install.sh will do the rest.

"pi-ap" has well documented instructions and even has a YouTube video to walk you through configuring it. HTH-