I had this problem when I first switched to PopOS, but I can’t remember how I fixed it. I think an update to something in Linux broke things again. I’m pretty sure that my laptop is using the DNS servers of the wifi that I’m connected to rather than the DNS of the vpn tunnel. I do see the tunnel DNS server listed when I do a systemd-resolve --status, but it’s at the bottom of the list. Anyone know how to get this working right again?
There was just an update to resolveconf, and it’s back to working. So, I’m guessing there was a bug that was introduced with a previous update.