WiFi dongle need to be re-inserted after every restart

Question

I'm configuring RPi as a WiFi repeater. Built-in WiFi module works as a main network adapter and configured to receive DHCP address. Second adapter Asus N10 dongle, meant to create a local WiFi network, detected successfully after inserting as wlan1 in addition to built-in wlan0. Problem is, after reboot interface disappearing from the system (ifconfig does not show wlan1) and I need to re-insert it.

I tried configuring /etc/network/interfaces

auto wlan1
allow-hotplug wlan1
iface wlan1 inet manual

and /etc/dhcpcd.conf

interface wlan1
    static ip_address=192.168.4.1/24
    nohook wpa_supplicant

No effect, adapter still requires re-inserting

UPDATE dmesg output right after boot gives the following messages

[4.348457] usb 1-1.2: r8712u: USB_SPEED_HIGH with 4 endpoints
[4.349986] usb 1-1.2: r8712u: Boot from EFUSE: Autoload OK
[4.605101] brcmfmac: brcmf_c_preinit_dcmds: Firmware version = wl0: Feb 27 2018 03:15:32 version 7.45.154 (r684107 CY) FWID 01-4fbe0b04
[4.605826] 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 
[4.977617] usb 1-1.2: r8712u: CustomerID = 0x0010
[4.977639] usb 1-1.2: r8712u: MAC Address from efuse = 30:85:a9:6e:5a:d9
[4.977650] usb 1-1.2: r8712u: Loading firmware from "rtlwifi/rtl8712u.bin"

30:85:a9:6e:5a:d9 is Asus N10 MAC address

After I re-insert the adapter, I see new messages in the output

[436.052089] usb 1-1.2: new high-speed USB device number 7 using dwc_otg
[436.184403] usb 1-1.2: New USB device found, idVendor=0b05, idProduct=1786
[436.184419] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[436.184428] usb 1-1.2: Product: ASUS EZ N Network Adapter
[436.184436] usb 1-1.2: Manufacturer: Manufacturer Realtek 
[436.184444] usb 1-1.2: SerialNumber: 00e04c000001
[436.187629] r8712u: register rtl8712_netdev_ops to netdev_ops
[436.187653] usb 1-1.2: r8712u: USB_SPEED_HIGH with 4 endpoints
[436.189124] usb 1-1.2: r8712u: Boot from EFUSE: Autoload OK
[436.613105] usb 1-1.2: r8712u: CustomerID = 0x0010
[436.613125] usb 1-1.2: r8712u: MAC Address from efuse = 30:85:a9:6e:5a:d9
[436.613149] usb 1-1.2: r8712u: Loading firmware from "rtlwifi/rtl8712u.bin"
[437.562399] r8712u 1-1.2:1.0 wlan1: 1 RCR=0x153f00e
[437.562936] r8712u 1-1.2:1.0 wlan1: 2 RCR=0x553f00e
[439.682544] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready

UPDATE2

Also I receive Under-voltage detected! (0x00050005) message during every reboot. Maybe it affects hardware initialization, I'm not sure

UPDATE3

ifconfig as requested

eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether b8:27:eb:f9:c3:2d  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 1554  bytes 185783 (181.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1554  bytes 185783 (181.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.38  netmask 255.255.252.0  broadcast 192.168.3.255
        inet6 fe80::f490:92fc:c558:8541  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:ac:96:78  txqueuelen 1000  (Ethernet)
        RX packets 16671  bytes 16141581 (15.3 MiB)
        RX errors 0  dropped 18  overruns 0  frame 0
        TX packets 11804  bytes 1416579 (1.3 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Asus adapter description, which appears after re-inserting

wlan1: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 30:85:a9:6e:5a:d9  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)

Answer 1

You are using Debian networking managed with /etc/network/interfaces together with dhcpcd. It is known that there are some quirks using this combination in particular with wpa_supplicant. What I mean you can look at Differences between /etc/dhcpcd.conf and /etc/network/interfaces?. I suppose you are also using hostapd and dnsmasq which are additional components needing there own configuration.

If you do not find a solution with this classic setup you may consider to give systemd-networkd a try. It is more straightforward and does not need additional components. It has everything built-in. You only have to configure it and it distinguish clean between the single interfaces wlan0 and wlan1. How to do it you may have a look at Access point as WiFi repeater with additional WiFi-dongle.