Hoping someone has come across this issue and learned how to fix it. Been trying to get Quake 4 LAN to work and I even recorded a video of what happens. It does not happen in any of the other Quake games so there is no frame of reference and it's frustrating. Could have Bethesda broken multiplayer for it?

Footage of Quake 4 severe hitching issue

I forgot to post my solution.

On a formatted install, my LAN server started working all of a sudden. Make sure to not play using the Quake 4 Tweaker. It's great if you plan to ONLY play singleplayer, otherwise don't install for LAN.

https://community.pcgamingwiki.com/files/file/1009-quake-4-tweaker/