Just checked and there were four such addresses used by Opera servers that were on the banned list. I have temporarily cleared them so you could perhaps try posting with your VPN on and see if that fixes it. Don't forget they may become blocked again if another poster abuses the board using the same ones in the future.

This may also be the problem for Tpebop, the OP of this thread. It is possible "the other place" may have had to ban someone and therefore blocked his VPN's address over there as well.