I have made dedicated servers on my computer with no mods and have zero issues but for whatever reason when friends join my modded server they are able to join but cannot move server side but are able to break some blocks close to their player and after about 5 minutes they get kicked due to a timeout error
sometime they can move and see me move but its about a 1 minute delay from when i actually moved
I am able to join and everything runs fine just not friends
I have checked my port forwarding and firewall many times over and there seems to be no issues and don't believe the mods are the issue but i could be wrong
My best guess is that when my server sends data to my friends the packets are to large or too slow for it to update 
I'm not the best with technology and would appreciate any help as I've been trying to fix this for about a month now and this is a my last resort
 

my modpack has around 150 mods but I've had this same issue on another modpack with around 80 mods
the only time i could get a server working was forge with no mods and i haven't tried with a small amount of mods

do i need to send any logs or does no one know how to solve this issue?

someone please help 😭

I believe this is the same issue but with a different mod maybe so if someone could figure out if a mod is the issue ill link the server logs below
Other persons issue: https://forums.minecraftforge.net/topic/123906-a-friend-of-mine-cant-join-my-lan-server-with-mods/

Logs:
https://paste.ee/p/5VeQS#s=0

Edited June 25, 20241 yr by Nawogers

 

Add crash-reports/logs with sites like https://paste.ee/

 

Do not use the OneDrive directory

Also make a test without Essential

 

I removed it from the onedrive directory and removed essential and its still just lagging for my friend
logs:
https://paste.ee/p/gtXpz

Also make a test without
 

Relics/OctoLib
enemyexpansion
enlightened_end

 

Same as before even after reinstalling the server and updating most mods
https://paste.ee/p/EkdNi
 

 here is my friends logs https://paste.ee/p/kAP4H

Edited June 26, 20241 yr by Nawogers

Is there the same issue with a pre-configured modpack from curseforge?

I just tried with better mc and my friend has the exact same issue although it takes about twice as long for him to join the server 

I just tried a server with only jei and create and my friend did fully load in once but now is doing the same as before
 
edit: he can join the server but just very rarely

Edited June 27, 20241 yr by Nawogers

Then it is something outside of Minecraft - maybe an issue with the Internet connection, Firewall or Antivirus program

I have no idea

ive checked firewall port forwarding dozens of times and im sure its all correct. my internet connection isnt insanely fast but still average. my friend has around 40 ping on the server.

ive tried everything and believe it could now be an issue with my router however from everything ive seen this is really weird behavior.

if anyone knows networking your help would be greatly appreciated.

 

I have run the server on a second device and my friend had the same issues as before where he was in the server and could move client side but nothing happened server side but any blocks he broke near his actual player did break but that was it, after a while he saw things move but it was around 2 minutes delay but this time he didn't get timed out

This leads me to still believe it is an internet issue but i have no clue what it could be as the logs say nothing about this and both of us have decent internet so maybe the router is limiting the amount of data that can be sent leading to the delay and eventual timeout.