* Actually the issue is quite general and can be applied to majority of DVR.
Can you give us more information?
1) there is video and all normal when view from locally connected LCD or TV via VGA or Video-out.
2) there is no change in port forwarding of router ( or un-known )
Most network DVR use IE to view without the need for additional software. Below focus on IE via network:
3) even on local LAN (without passing the router), on IE still cannot view video but can control PTZ
4) using two computers to try, same result, video not seen
5) you can open the IE interface, just not seen the video, buttons, controls can all be seen, right?
6) then the video area is blue or black or whatever?
7) do you still see the grid when quad splitted the screen?
is there video recording? can you view playback?9) can you give us the DDNS domain, user and password, let's visit to check for more information?
10) are you confident to detach the motherboard from chasis and return it to us for repairing, if finally need?