So a couple of questions for you, is your PMS running from your laptop that is a bridge? or is it running on some other computer on your internal network?
Is the PMS Server on the same layer2 network as your PS3? The reason I am asking, is that if you are using a laptop as a bridge, with multiple network adapters, it could block the PMS broadcast messages from one side of the network to the other.
My understanding is that the PS3 Media Server uses broadcast messages and sends out sends out discovery messages, and as broadcast messages are blocked by routers and bridges, so they will not make the jump.
if your PS3 and PMS are on different subnets or networks, your bridge will not forward broadcast messages. That is the core design of a bridge, to isolate broadcast domains.
this info is from basic networking, I haven't dug into the PS3 media server to figure out if it is indeed using broadcast messages (but thats what the log files indicate).
Best bet for troubleshooting would be to plug your PS3 into the same layer2 switch as your PMS and see if it works that way. Be sure to have both systems on the same ip subnet as well.
Don't go by what the PMS tells you, look on your PS3 XMB and see if it detects the media server. Oh and be sure to enable the media server connection under the PS3 network settings.