I have installed these mods:

Server log:
11:49:32] [User Authenticator #4/INFO]: UUID of player _Boas_ is 0e195094-3422-427a-81b4-d17b34b820cf [11:49:32] [Server thread/INFO]: _Boas_[/127.0.0.1:55026] logged in with entity id 326 at (10.5, 79.0, 30.5) [11:49:32] [Server thread/INFO]: _Boas_ joined the game [11:49:32] [Server thread/INFO]: _Boas_ lost connection: Disconnected [11:49:32] [Server thread/INFO]: _Boas_ left the game [11:49:32] [Server thread/WARN]: handleDisconnection() called twice
Client log:
[11:49:02] [Render thread/INFO]: Connecting to localhost, 25565 [11:49:31] [Render thread/INFO]: Disconnect from localhost [11:49:31] [Render thread/INFO]: Connecting to localhost, 25565

It was fixed when I removed the ForgetMeChunk mod on the client

This mod is client side only, the server will break if you install it there.

Sorry I said it wrong, the server doesn't have the mod

This mod is client side only, the server will break if you install it there.

it wont it just wont do anything

what minecraft version is this? and mod version

actually i think i see the problem, your using debugify, it contains the exact same fix as this mod, if it still happens without debugify installed, please re open this

i also recommend you read the readme for this mod, the fix used here and in debugify, is at best a hack and causes a memory leak, so make your own choice on if you want to use the mod knowing that it causes a memory leak (read the readme for more context)

oh yeah I just downloaded it as it said it was a performance mod lol

1.19 newest version

Could we please have this mod categorise Debugify under breaks? It took a very long time to figure out that this was the root cause.

Or should I be asking the Debugify devs to implement that instead?