I have a strange cause of disconnection from me and my friends server. When I log-in on our server and spawn in the End dimension, I experience no issues at all, I can even grind in our Endermen xp farm without experiencing any lag, but when I go to other dimensions, I eventually get disconnected from the server, showing messages such as "Disconnected", "internal exception java.io.ioexception an existing connection", or something similar. The only solution I find to this problem is when I use some sort of free trial premium VPN service, but this is only for the short-term.
We run our server using PaperMC 1.16.4 software and my friends don't get issues like this.
What is/are the possible ways, in order for me to get rid of this issue completely?