i have a similar problem . i have 5 DCS 920 in my store, the ISP at the store is Verizon DSL. at my home, i also have Verizon DSL ISP , i have static IP's for all cameras, i have an account set up with a DNS and have IP Config Updater running on a pc at the store that is always on, port forwarding on the router at the store are all set correctly, i can view live video from home and from any one's network that is using Verizon DSL
BUT, when ever i am on any other ISP's network, such as Comcast cable or Sprint Broadband, i can't get the live video . i can get to the camera, change controls, etc but the video is somehow blocked . it's not an issue with PC , anti-virus or anything else- it has something to do with the ISP blocking the video portion of it, and i have not been able to get a solution . the DCS 920 has the ability to enable a second port which i have done, 8080,8081,8082,8083,8084 for each of the camera . i remotely reach the cameras using the DNS name with :8080 , :8081 etc for each camera - any one out there that can help me resolve the blocked video on non-Verizon DSL ISP's would be appreciated. i have once read that the DCS 920 uses port 80, but i can't confirm if it is true for the video portion, does it use UDP 9000 ? when i enable the second port 808x, i think that's just for TCP purposes , so that i can remotely reach the camera's internal LAN static IP through the port forwarding i have set up in the router. does the video portion coming out of the camera use UDP 9000 ? i am no TP expert, so don't mind me if i sound confused.