I'll try to be as verbose and detailed as possible. I also have a video of the issue taking place.

I'm hosting a Minecraft version 1.21.1, NeoForge version 21.1.208 server for friends on my computer. Alongside Immersive Portals and it's dependencies, I'm also running these mods (filtered to what I believe might cause said issue. I can provide a full list if necessary) :

• Create (and it's extras)
• bad packets
• Entity Model / Texture Features
• Lithium
• Sinytra Connector (HOWEVER, I'm running the NeoForge version of Immersive Portals, so it shouldn't be touching Sinytra at all. But I'm not entirely sure if Sinytra's very existence within the server causes this issue, so I'm still listing it.)

Whenever I or another player go between dimensions via an Immersive Portal, there's a chance that everything will freeze, blocks will no longer become interactable, and after a short time, everyone gets disconnected with a SocketException error, including myself. On the server's end (Me and my computer), my outbound internet will cease to function, shortly followed by my inbound also ceasing, making my computer unable to use the internet. The only way my computer can recover from this state is by restarting the entire thing.

There's no Immersive Portals-related errors or warnings in the server log whilst everything is running. However, when the issue suddenly occurs and everyone is disconnected, I'm given a fatal exception that's supposedly debug-only?