addnode in bitcoin.conf doesn't work (Regtest mode)
well im late but i can tell.

it works, use following string

addnode IP:8333 add   but the Port you dont need to show, because everyone uses the same port, because thats the one he set as open on his router. the rpc port must only defined once at startupt. in addnode dont use it, because you could be bound on an IP too via the bind= command, then the server dont know what to do.