Frequency band set to 2.4GHz but reverts to 5GHz

[simonbogh]

Describe the bug
I have a setup with a Raspberry Pi 5, Ubuntu 23 running a hotspot at 2.4GHz and everything works great for some time. After a while the hotspot reverts to 5GHz, which means my 2.4GHz devices cannot connect anymore. I need to restart the hotspot for it to use 2.4GHz again. /etc/create_ap.conf shows correctly that FREQ_BAND=2.4

Installation is done from source.

To Reproduce
Steps to reproduce the behavior:

1. Create a hotspot from the GUI with Frequency band at 2.4GHz
2. Connect device
3. Wait ..
4. Hotspot reverts to 5GHz and 2.4GHz devices cannot connect anymore

Expected behavior
I expect the hotspot to run exclusive at 2.4GHz and not 5GHz.

Desktop (please complete the following information):

• OS: Ubuntu
• Version 23.10

Additional context
I am running the Raspberry Pi 5 as a client and hotspot. I connect it to my local network for internet, and run a hotspot for other devices to connect. It works great for a while until it changes the frequency band.