Does your modpack have custom mod (Ex. for optimisation) ?

Do you have any logs / crash logs ?

it has no custom mods, the game never crashed, and the minecraft logs don't seem to say anything useful (from what I can see, but im not the most experiences with mods)

https://pastebin.com/dqNStWGN - minecraft log when joining to become stuck on loading terrain screen

https://pastebin.com/Sd1ag2Nv - minecraft log where I dont get stuck on loading terrain but still have completely frozen chunks

Yeah... you fully log in even on your Loading Terrain, if you could send one or two debug.log would help to identify clearly the issue, tho I would also recommand checking if you have your Ram set up to 6+gigs, if yes and that didn't help in your instance config try disabling FlyWheel optimisation :

../.minecraft/config/flywheel-client.toml

Change

#Select the backend to use.
#Allowed Values: OFF, BATCHING, INSTANCING
backend = "INSTANCING"
#Enable or disable a debug overlay that colors pixels by their normal.
debugNormals = false
#Enable or disable instance update limiting with distance.
limitUpdates = true

to

#Select the backend to use.
#Allowed Values: OFF, BATCHING, INSTANCING
backend = "OFF"
#Enable or disable a debug overlay that colors pixels by their normal.
debugNormals = false
#Enable or disable instance update limiting with distance.
limitUpdates = true

And retry, if that didn't helped at all, I recommand you try to install some optimisation mod like Embedium or Ribidium at your choices

the log is too large to send as a file or paste into pastebin, what way do you recommend sending it?

Changing the config and downloading embeddium both weren't able to fix the problem of chunks freezing, unfortunately.

What are you Java argument and how much ram are allocuted? tho imma be honest I don't really know what to say because without clear log and being unable to replicate bug since you are the only one having it for now.

I could also recommand trying using the Adoptium Java (you can download it via Prism directly)

my java arguments are completely default, I'm giving it 8gb of ram, but the issue still persisted when I bumped that up to 16gb.

I did download adoptium and the issue is persisting

https://justpaste.it/cj6bb - my full debug.log

After parsing your logs, there is clearly no issue on loading mc, then loading inside the server, your clients register fine while also receiving everything fine from server while not having any issue on server.

Honestly right now I can't really tell why you are only you getting this issue

Issue Marked as Done

Problem: Connection issue as by using wifi sadly the only fix is either getting ethernet cable or a better connection towrd the router.