Thank you for your answer.
Sorry for my mistake in the formulation. What do you mean by "add some tags" ? (I am not used yet to this wiki !)
Coming back to the question:
I tried to change the default IP adress from 192.168.2.1 to 192.168.1.1,(in the LAN section, as you put it) in order to change of subnet, but it is not working !
I get a "Failed to confirm apply within 30s, waiting for rollback…"
Is there somewhere a detailed explanation how to do it?
Your help is much appreciated.