So I install surveillance video systems for commercial and residential applications. I recently noticed two customers having this issue with an xfinity modem/router. Two different model routers which I dont have at this time. The issue is as follows:
I use a DDNS client for the DVR/NVR due to dynamic IP addresses. I open up ports 80 and 8000 so it can be accessed remotely. I can access the systems remotely with no issues when I am not attached to the wireless router on the same network the DVR/NVR is attached to. When I am on the network, I cannot access the DVR/NVR when I am going through the DDNS website. If I use the IP address assigned by the router (i.e 10.0.0.4) it works, but for some reason the router is blocking the DDNS website when I am on that network. I disabled the firewall and still had this issues. Comcast of course is no help on the phone and is blaming the DVR/NVR. I pretty confidant there is a setting on the router that is causing this issue.
Was wondering if anyone knows
Thanks in advance
Yes it sounds like NAT loopback, or lack thereof, is your problem. You will likely have to ditch the Comcast issued router and get something better. You can check this site for a list of routers that are NAT Loopback compatible: