Error doesn't seem to cause any issues, still curious what could be causing it.

the [16:42:16] [Netty Epoll Server IO #0/ERROR]: Error sending packet clientbound/minecraft:disconnect?

Yes, that's the one.

If you are referring to the server sleep feature that Mojang added in 1.21.4, it is probably best to disable it via server.properties pause-when-empty-seconds to -1

It does not play well with modded or plugin server espcially if the mod/plugin are listening to stuff per tick.

but honestly, if you do not really expererience issues and that error is the only thing that shows up, it's really just up to you. I dont think the pause feature is that important unless you are self-hosting and want to save some small energy cost.

https://modrinth.com/mod/log-begone you can always use this mod to remove logs you dont like that cause 0 issues but just show up

I didn't realize that feature could cause issues, I'll try disabling that and seeing what happens.

In the event that the sleep feature isn't the cause, I'll definitely be installing this to remove it from the logs.

I've never had an error that does nothing like this so I figured I'd ask, thanks for the quick response.

you regex it out, so you can pick and choose anything