strange lag/desync issue

So me and a couple friends made a calamity world and I have been having little desync issues, nothing by major until we got up to cryogen, we started having insane issues constantly but only when one of them joins, if the other joins there’s no lag at all, he restarted his wifi and it fixed for a short while and then goes back to being so desynced that we kill a boss and he’s still fighting it, does anybody know how to fix this?
Was this page helpful?