I've seen this topic discussed but I haven't seen any real root cause or solution.
I have a dlink 655 router.
I hooked up a dlink 942L.
I never got the Live Video timeout on mydlink.
I then added a dlink 930L.
Now BOTH cameras get the timeout on mydlink Live View.
I have UPNP enabled on my router.
I also tried enabling the UPNP port forwarding, but this did not help.
I get the timeout on both Firefox and Microsoft IE browsers.
UPDATE:
I did a port forward rule (for port 80) on the ip address of the dlink 930L.
Now, this device does not get the timeout in mydlink.
However the dlink 942L still gets the timeout.
You cannot forward the same port number on two different IP addresses.
So I still need help.
Any help would be appreciated.