@Skar78:
I seem to have a related issue. However I am a beginner user and might simply miss something trival or missjudge my case.
Once in a while my ISP shuts my connection down (they do this automatic here (Taiwan) upon late payment - and my wife frequently "forgets" do transfer the money.
In this case it seems like they switch off the port on their side - the DSL modem can simply not sync the DSL line.
However pfsense behaves very strangely. Apinger service basically shutsdown and cannot be restartet and also the wan port is disabled.
If i manually enable the wan port it has no effect (stays disabled) and apinger basically never recovers and cannot be restarted (apply changes -> reloads and no change).
If i re-create the wan interface it worked last time, meaning i deleted the interface and created it again.
As i have the opportunity to face the same issue again today I plan to try a re-boot first.
Ok i tested this again. Reboot and disable/enable did not work.
What I noticed is that i need to assign the interface from its pppoe1(cuau0) to the vr1 again and re-enter login/password - only than it would work. Why i have to do that i dont know.
Everytime this happens it looks like pfsense would increase the index of the pppoe interface and add one bound to cuau0, why pppoe would be assigned to the serial port, no clue.
However this issue is different from OP, so sorry my bad.