Well I will RMA the device now. Its 20 months old, and Just now i've been using the PPPoE feature figuring its broken. You can't tell me having to configure MTU on endpoints is a desired feature.

Hey, I have a quite similar issue regarding ER8411, and PPPoE WAN: Most of the http/2 traffic, especially in apps like Cursor, Docker on Windows (in WSL) did fail until i set the MTU on the windows...