Here's what's causing it:
The server is trying to compress packet data and failing when you mess with your inventory. Usually happens with modded items that have a lot of data attached.
Quick fix:
Add this line to server.properties:
network-compression-threshold=-1
That turns off compression. Should fix it.
If it still happens:
Make sure everyone has the exact same mod versions
Give your client and server more RAM (like 4-6GB each)
Update your mods/Forge
The inventory thing makes sense - modded items with tons of NBT data can mess up the compression. Turning it off doesn't really hurt performance on most servers.
By
setria ·