- Why is the “Enter IP Address” set to 174.21.130.19? That is not the Internal IP address of the Tablo. The internal IP of the Tablo should start with 192
- It appears your combo modem / router cannot do port translation (which is forward an external port to a different internal port), which is what the Tablo needs. This is a limitation of very old modem / routers. You can only forward external port 8887 to internal port 8887 for example.
- Your C2100T does have a UPnP page, go to it and turn UPnP on. Then try having the Tablo do the port forwarding automatically (go to the Settings page in the Tablo and turn off and on the Tablo Connect feature).
See thread below.