I've never dealt with DHCP option 82 so I can't speak to that, unfortunately, although it sounds like that might be the cause of your issues. With the old ONT it's handling that for you instead of just passing things directly on in bridge mode.I would recommend turning on the gateway monitoring as well as using your ISP gateway to test your connectivity as you don't want to add additional complexity when your problem is definitely in the last mile.
So my journey into this investigation has come to an end... finally. So after having a few email threads with my ISPs tech support and a few calls with them to confirm a few things. It looks like what might have happened was that one of the field techs might have assigned my static IP address to another ONT. So I decided to just power everything down, including the ONT and then "sleep on it" hoping that the 12-hour DHCP lease would expire, both on my end and whatever other ONT accidentally got my static IP address bound to it.Woke up in the morning, did another clean install of OPNsense (just to be sure), powered on the ONT and everything works again.Thanks for everyone in the thread for the suggestions! turns out the ISP just had a "whoops" moment.
