PPPoE over an unassigned VLAN no longer connects after upgrading to 26.7.3

[johndoeuser]

I want to chime in to this thread. I seem to have exactly the same issue as OP. A (Dutch) KPN fiber connection. PPPoE configured over vlan6 tagged interface. PPPoE works flawlessly up to version OPNsense 26.7.1_1-amd64. At the moment I have a cold stand-by with a clean install and upgraded to OPNsense 26.7.8_2-amd64. I only configured PPPoE which still doesn't want to start working. Help?! ;-)