Yes, it is possible to establish an access point and connect the RasPi as client to your internet router at the same time only with one WiFi interface. It is able to use the physical interface wlan0 and create a second virtual interface ap0 on the same device. There is no need to use an additional WiFi dongle. How to do it you can look at Access point as ...
So to elaborate on the full solution here:
priority=1 #lower priority
priority=2 #higher priority
Then after initial reboot, to actively switch networks (without a secondary reboot):
sudo wpa_cli list_networks #...
I cannot see what the script you used is doing. It is two years old and at a glance it modified /etc/dhcpcd.conf and use /etc/rc.local. The former should be used with caution as noted by the author, the latter is deprecated. You should better ask the author and reed the issues.
But you wrote in a comment:
What I want is just a routerless wifi to which I can ...
If you know what the problem is, you can use an existing Linux device to view the files on the SD card/SSD/HDD/etc.
If you only have a Windows device you may be able to use external programs to view EXT4 or you can boot off of a Live USB.
Then you can edit the configuration.
For some reason you are not getting an IP address for this Pi.
The 169.254 IP range is the Link Local range for IPv4 and normally set if no DHCP server is acknowledging your request for an address.
This could be due to:
You not connecting to the Wifi
The network not allowing you an IP address (possible MAC filtering)
The DHCP server being down
All IP ...
The (very) small WiFi antenna on the Pi makes it susceptible to interference. Other, distant SSIDs on that channel may not hear the Pi and talk over it. Also, if there are networks that aren't on the set channel but do overlap it, the traffic there becomes simple interference and may also drown out the Pi.
Use a WiFi analyzer (there is at least one free ...
You can also the rfkill command to disable or enable the Wi-Fi interface(s). This is how the interface is disabled by Raspbian with a new installation before the country has been configured in the Wi-Fi settings (e.g using raspi-config). You can disable the Wi-Fi interface(s):
sudo rfkill block wifi
Enable it like this:
sudo rfkill unblock wifi
And check ...
I have several Pi's that run 24/7 and they will automatically reconnect when the wifi is available (I deliberately have my wifi networks turn off at night when there is no need for them to be on). I have found the below to be 100% reliable. I am using static IP on my Pi's but it should work fine with DHCP as well:
sudo nano /usr/local/bin/checkwifi.sh
The default dhcpcd is reliable and will automatically connect if correctly configured. See How to set up networking/WiFi
Raspberry Pi OS DOES NOT use networking.service - unless you misconfigure it.
You can use NetworkManager, but it is difficult to configure manually, and the GUI networking tool in Raspbian won't work. It is no more reliable than dhcpcd. ...
I assume you are using the Raspberry Pi OS. You want to boot the kernel from the SD Card because network booting the kernel with WiFi isn't possible. But you want to use the root partition from an NFS export. This could be possible if the remote filesystem is available before the kernel switches to the root filesystem.
As you can see at bootup — System ...
Using Andbdrew's tips above I was able to make this work headless (and with a head) consistently without disabling Cloud-Init. Thanks to @enconn, for brainstorming and a link to https://cloudinit.readthedocs.io/en/latest/topics/examples.html#reboot-poweroff-when-finished.
Image the SD Card using Raspberry Pi Imager v 1.3 selecting the 'UNBUNTU 20.04 LTS (...
it seems there is a problem to coordinate all the additional helpers. But there is an easy way to just configure the Raspberry Pi OS with no need to install additional programs. You can use systemd-networkd to do all things. It has all needed features built-in. You just configure it, what make thinks lean and well-arranged. You can look at Access point as ...
Same issue here with a Raspberry pi 4 model B Rev 1.1 using the on-board Wifi. I am using this Raspberry as a WiFi access point. This issue happens one or two times after a day of normal use. Usually when here is a lot of traffic in the network (copying files, or reproducing video with the Chromecast). After this happens, all wifi-clients are disconnected ...
The channels are set by your wireless access point, and the country you live in. USA only has 12 distinct channels. Some countries have 14... not in USA. You can set you WAP to 3 distinct channel spaces & not compete or overlap with a neighbor.
1, 6 or 12 give you the widest ranges with fewest chances of overlap. It is something you have to play with ...