I have a RS2000 G8 server with 4 CPU and I'm having problems with large (>1472) SIP (UDP) packets which have a loss of almost 100%. Of course changing to TCP fixes the problem, but not all users can switch so easy. I have servers with 2 other providers where there is 0% packet loss. Support was helpful and changed me to another rack, but still the same problem.
To test, I'm using socat on an open port like this:
socat -v UDP-LISTEN:35000,fork PIPE
and send packets from a remote server with udpping.py (https://github.com/wangyu-/UDPping/blob/master/udpping.py). This works 100% to one of my other servers, so I think the test is correct.
Today I did a final test and tested in recovery mode with the same results. So now I'm out of idea's and hope that someone can help me.