Cannot enter caves connection issue? Xbox One

I've been looking everywhere for posts videos absolutely anything but I haven't seen even one thing on it except for one obscure post about dedicated servers. So the issue is me and my friend play on xbox together and we've noticed that he can't enter caves. I can just fine but if he ever tries to join from any sinkhole he gets an error message about unable to connect to server. I have no idea I've tried all I can and there was no info on this causing me to have to make an account so I can beg for help or any info