I was wrong… my server router started to have unstable wi-fi, disconnecting clients, I guess a byproduct of the downgrade.
So, risking it all, I upgraded again (only the server) to 4.8.2 and did a side upgrade for Adguard (found it in another post: [TUTORIAL] - How to modify Adguard Home on GL.iNet devices to enable webui without logging in to the admin interface ).
This stabilised the wi-fi functions and then went into Luci to try to discover why the Wireguard clients were not talking to each others and found under Firewall - Traffic Rules the following rule: wgserver2wgserver configured as Drop changed it to Accept and voila, everything is working as before.
Then I decided to test and upgrade one of the clients to v4.8.2 and there is definitely an issue here that needs investigation, while the server is working well, the client I can only have Wireguard or Adguard working.
As soon as I activate the VPN Adguard cannot connect to upstream servers. I tried to tweak fw rules, etc. nothing works. If I stop the VPN, Adguard works without a problem.
For now I’m taking down Adguard.
@bruce do you guys know what’s up?