I’m pleased to confirm that the server is back online. Thank you sincerely for your help.
I used the TCP Optimizer program to determine the exact MTU that’s appropriate for my connection, and set it accordingly. The server was indeed restarted each time I set a new value.
At first, there was no change, even when trying other MTU’s, but the errors no longer occurred the day after.
While I’m not 100% sure what finally fixed the issue, the new MTU value is mostly likely to credit. I wouldn’t have thought to check this on my own.
The server’s presence now reflects on flserver.de once more.
Thanks again!