So I have a problem with my server. I can play it just fine, and so can my friend. However, if we log on at the same time, we both crash. Not only that, but I found out that if we're far apart we can play just fine, and it will crash when we get close. It is a modded server, we have the same mods and same forge installed. I don't think it is a problem with the mods, but probably related to forge.
Crash Report: