This may be a networking forum question, but my initial thought is that perhaps it's timing out as part of a setting in the router.
Unfortunately, I can't assist with networks and router settings, but I believe that's where the problem would be.
I have just purchased a BluRay BD-C6500 and connected it to my wired Shaw Network via a regular router, I have never had any issues with the router. I loaded some test photos and music on to the PC Share Manger Server and the Server name will show up on my Sony TV screen for a limited time only. I select the PC Share network and access my photos and music, unfortunately after a few minutes playback abruptly stops, and the PC Share Manager server has dissapeared from the pull down A list. I am able to continuosly select from Windows Media, so the Network connection is solid, unfortunately Windows Media Libaray selection is slow on the BluRay. I have Windows XP, completely up to date, and am using Shaw Secure security software and Firewall - note Shaw Secure is a product from F-Secure. My Windows Firewall is turned off. I can restart PC Shaer Manger and it wil again work for a mited time. I have tried turning off media sharing in WMP in case there is a sharing violation, but no sucess. Any suggestions?