Caves loading/ and disconnecting

Me and my friend are on day 72 of a new world and he can’t enter the caves. After about a minute he just disconnects, from the server. We are both lan lined in at 200+mbps. We have long autumn on so it’s summer and we jumped into the caves to escape the heat.

he can no longer rejoin after the disconnect. We had this problem a few years ago, and hadn’t played until recently. It really kills the game, for both of us.

if I roll the server back to before he enters the caves. he can rejoin the world and play on the surface. but still caves boot him every time. 
 

this is on PlayStation 4. Sorry idk how to move it and don’t want to double post.