Hey, I’m having the exact same issue. From host side, it says it “failed to find an existing connection with a matching cookie”, and from the client side, it says “PacketHander isn’t fully initialized and also didn’t fully consume a packet! This will cause the connection to try to send a packet before the initial packet sequence has been established.” Also, it says that remote address’ PC is NULL, Owner is Null and UniqueId is NULL. I cannot seem to work this through.
Have you maybe found a solution? Also, when testing remotely, I am sometimes able to join as client, but most of the times, I am not.