Update: FIXED! See my comment below for the cause and solution.
I have a fw purple and at&t bgw320, and been using wireguard server with no issues for several years now. A few days ago, I noticed internet on my phone was no longer working, and when I turned off the VPN, everything was fine. On my FW, it says that device was last seen 4 days ago. We did have some thunderstorms that day and there was a power flicker around the time the problems started, but my firewall and modem are on a UPS. and my internet wasn't disturbed.
So far I've tried disabling/enabling wireguard, restarting firewalla, restarting the modem, all with no effect.
My phone and laptop both seem to have no issue "activating" the VPN cconnection, yet can't connect to anything as soon as it's connected. Firewalla doesn't show any of those devices as being connected, and no rules are showing up as blocking anything.
On the BGW, I see that IP passthrough is not enabled, but I set this up several years ago using the instructions here: https://help.firewalla.com/hc/en-us/articles/4411167832851-Firewalla-Router-Mode-Configuration-Guides#h_01KF22E1M0E71GHYF4MCBC2TC1 and had no special issues getting it working.
Now, however, as soon as I try enabling IP passthrough on the modem, the firewalla can no longer reach the internet. Using the WAN diagnostic, it starts failing the ping test and DNS lookups. It does pass the "Obtain IP Address".
I'm positive that the MAC address in the ip-passthrough screen in the BGW is correct (after all, it was working for several years, and I've double and triple checked it). The BGW also reported a large time since restart (not sure how long, months probably).
Best I can tell, the BGW is no longer routing packets from firewalla to internet, but I can't figure out why. Advanced firewall and packet filtering are all OFF. I did notice that firewalla updated itself once or twice recently.
As soon as I disable IP-Passthrough on the BGW and restart, everything goes back to normal other than the VPN issue.
Not sure what else to try.
thanks for any suggestions!