BTW, I have P8 forwarded to VOIPo number.

It looks confusing to have the P8 phone still as one of my two lines, because P8 still rings once or twice even though VOIPo is ringing (And that is P8's forward option - not simul-ring.) So I am leaving P8 unconnected to any phone.

Forwarding should not interfere with my P8 LNP to VOIPo. It never affected Vonage to P8 ...