Automatically start an access point on a Raspberry Pi 2W when Wi-Fi is lost

[mot94]

Good afternoon!

I have a task to make my Raspberry Pi 2W more autonomous. The main idea:

Goal: Implement automatic startup of the built-in access point (AP) on the Raspberry Pi itself if it loses connection to a known Wi-Fi network. As soon as the connection to the main network is restored, the access point should turn off.

What I've already tried and the problems I've encountered:

Attempt via scripts and systemd: I tried to write a script myself that monitors the connection status (via iwconfig, ping, or nmcli) and manages the hostapd service. I consulted with DeepSeek, but my experience is currently insufficient to make this work stably. The scripts either didn't trigger or led to network configuration conflicts.

Attempt at backup connection to a phone: I tried an alternative option — to configure the Pi to connect to a mobile hotspot as a backup network. But here I encountered another problem: the Raspberry Pi 2W for some reason does not see my mobile hotspot (Xiaomi 12 lite phone). Other devices see and connect to it without any problems. Perhaps it's an issue with the channel settings or the Wi-Fi standard on the phone?

My configuration:
Board: Raspberry Pi 2W (built-in Wi-Fi)
OS: Raspberry Pi OS (64-bit)
Network manager: The default one (dhcpcd) or NetworkManager?.
When adding an access point, they select the RU region.

Main questions:
Does anyone have a ready, working solution for such a scheme (main Wi-Fi -> AP when disconnected)? I would be very grateful for links to scripts, instructions, or projects on GitHub.

What is the correct architectural approach? Is it better to do this via:
A systemd unit with a timer/service?
A combination of hostapd, dnsmasq, and a custom daemon?
Ready-made solutions like create_ap or wifi-connect?

Problem with the mobile hotspot: Has anyone encountered the issue where an RPi does not see hotspots from certain phones? Which direction should I look into? (Checking logs dmesg | grep wifi, region configuration, forcing the 802.11n/g standard?).

This is my first experience using an RPi, I will be glad for any help and advice.

Thank you!

[phattmatt]

Hi @mot94,

Welcome to the project!

There is a similar request here: #281

Regarding your Raspberry Pi Zero 2W not seeing your phone hotspot keep in mind that it only supports 2.4Ghz WiFi networks. I've also had some problems with WPA3 in the past, so maybe try WPA2.

Good Luck!