Trouble with D-link 5300W webcam. "failure to connect server"

Hello there.

I just got this camera for my firm and been testing it at home. I had
initial problems with my ISP IP leasing times, but enabling NAT
corrected it. With NAT the camera works flawlessly in LAN enviroment.
But the trouble began when connecting from the internet side.

I have used Virtual Server on my ADSL modem (Telewell EA-400) to
forward ports 80,5001,5002 and 5003 to cameras NAT IP. But when I
access the camera from outside, the picture runs ok couple seconds,
halts and after a while gives an error message "Failed to connect
server". Configuration screens work ok, but the screens with Video get
stuck.

Iam pretty clueless about this one, since I have forwarded all the
neccesary ports for NAT and there is no hardware firewall at my home.
To clarify the web cam is directly connected to my ADSL modem.

D-link support was very helpful. "Try restoring the factory defaults
and configuring the camera again" :)

Sorry for the bad english, any ideas about this one?

.