Both routers operate in router mode, both have DHCP enabled and both have UPnP enabled. The PS3 is also added in my WLAN routers DMZ. The main Router Modem goes in LAN 2 of the WLAN Router and my PC goes in LAN 3 of the WLAN Router. Nothing goes in WAN on the WLAN Router.
I also forwarded some ports I found on playstation.com to the PS3 in the WLAN router.  

For easier understanding here's a pic of my Network (I photoshopped the PS3 in since without UPnP it can't appear there):



EDIT: Nevermind I just installed TVersity and the PS3 picked it up fine^^