Wifi Problem Fritzbox 4040

good afternoon,
For a few days I have been having problems with the Wi-Fi connection. My devices connect and disconnect and this causes me to have problems with my smart home devices.
I have a Fritzbox 4040. If I have done anything, it has suddenly started to create these problems.
Does anyone else have this and how can I fix it?
Thanks a lot

if I can help ...
I have the same model for now no problem

original firmware or openwrt?

if openwrt:
make sure you have the correct country
in the / etc / config / wireless file

check that the channel or channels you are using are not among those that are subjected to "DSF"

post the contents of the file
/ etc / config / wireless
obscuring the password lines
option key 'a-very-secure-password'