Stuck on Locating Server

My son and I play together, him on Nintendo Switch, me on PC, we have been playing on a server created on my PC without issue. Yesterday he was disconnected from our server randomly while caving and now his screen gets stuck on "locating server" whenever he tries to join.  He is able to join all of our old servers and any new ones, but not the one we wish to join. On my end, his character appears in the world, but it does not notify me that he has joined.  Oddly enough, when he cancels the request to join the server it notifies me that he has left.

Thank you,