Problem with connection

So my friend can join the server but within several minutes he gets timed out. We tried so much things to solve this problem like allocating more ram on launcher, reinstalling the game but none of these solved the problem. But in other servers (Not Aternos), there is not a problem. Does anybody know how to solve this?

Edit:The server is Paper and 1.18.2 btw

Yes, 10 seconds before the error he can't collect any block and players freeze on his pc. Sometimes it doesnt give the error and he leaves the game because of these problems.

We are playing with 10 players but he is the only one that gets this error. He tried to connect with dynip but the problem is not solved yet. I set the randomTickSpeed to 3 and it didn't work too. I first thought it's because of his pc but when he joins other servers(Not Aternos), this problem doesn't happen.

Ok but I didn't understand the last step. Do i need to open a server from my pc?

Ok, sorry for the late answer.

Main Ip: devletlermc.aternos.me

Dyn-Ip: smeltwhiting.aternos.host

Public Ip: 92.45.223.77

Country: Turkey

Username: lightzz0

Software: Paper 1.18.2

The problem didn't occur when he installed java software and I added the traceroute results in Attachments.