Problems with connecting

You're not making much sense. "Boxes" is very non-descriptive. I have lots of boxes; most of them are cardboard and have nothing to do with networking.

The TECHNICOLOR tc8305c is a combination cable modem/wireless router/VoIP adapter. I assume/hope that the Comcast coax cable is connected to the TECHNICOLOR tc8305c. Please describe the remainder of your network using terms like "router" and "switch" and "ethernet" and "wireless" and "computer" instead of "boxes." :)