This was updated because people believe it's performance lag, when it's actually network lag, here is an updated version of mine. So, to summarize, When I was on a survival server, the website that the owner was paying on for, optimized it to 1.17, but network latency overtook it and caused chaos.

The server was using spigot for some plugins like a anti cheat or 1 person sleep .

The server's owner stated, the network slowness issues were not there while the server was at version 1.16.5.

It used to be that 6 people could join it, however with the change from 1.16 to.17, only 2 people may join it without it crashing and restarting.

Mostly people are using normal Minecraft till Optifine comes in for 1.17 but I'm using the pre-release of 1.17.