Playstation 3 and Tversity media server

For weeks I've been trying to figure out how to get a stable connection from my PS3 to a Tversity media server on my network.

FINALLY I've found the solution, and it was of course very simple...

Here's my setup:
Playstation 3 patched up with the latest software.
Wired connection to a D-link DIR-635 router.
A desktop PC is set up with Tversity as the media server and this also has a wired connection to the router.

The router creates a NAT for my home network. There are two desktop pc's, one laptop connected wirelessly, and the PS3.

When I tested the connection properties on the ps3, I always get uPnP "Not available" although it should be possible through the router with the uPnP-setting set to "on".
"Nat type" is also Type 3 - which warns me that some game features might not work - and for a long time I was sure this was the source of my problems with the media server not working.

However - from time to time I was actually getting a connection to the media server, but not always and I never understood why - until today.
Today I tried quite a few things, and suddenly it struck me - my vpn-client!

I have a Check Point VPN-1 client installed on the desktop PC to be able to connect to the network at work. I'm usually logged into that, and today I just shut down the client, and what happened? - The mediaserver popped right up...
God - did I feel silly...

So know you know - ps3, tversity media server and vpn-client - not a good mix.
Nat type 3 is not a problem which I thought...

I will soon install a home server on my network which will be the new media server, and there will be no vpn-client on it, so then there won't be a problem. For now I just have to live with the fact that I can't stream content from my computer on the PS3 when I'm connected to the network at work.