Hello,
I wonder if this issue is related to 1.94 -> 1.96 upgrade. I'll try to help you but I need more information:
1. Most of all, I'm interested whether this is our favourite "No message received .." problem? Did you see this message in 1.96?
If you receive "Player XXX is losing connection" message, it indicates any type of network connection cut-off between XXX and the server.. (including XXX client crash/freeze/etc.).
Only cases with coincident "No message received .." (on the XXX player console) and "Player XXX is losing connection" (on all the other consoles) could be related to a flaw in low-level network code.
2. Do you use personal firewalls? Which types/versions? Which security levels are they set to? And do security levels affect frequency of your problems?
I welcome any relevant information, you can use my PM as well..
P.S.: And I must say - Ondrej was truth - we did no changes in our network code since 1.94(hotfix).