missing channels on new x1 box

Hello, I'm having some odd behavior on my primary cable box (Coax) and suspect the issue is the physical cable.

- A few days ago, my older box stopped working. The picture was just all distorted across all channels.

- I got a new box at the Xfinity store. This box never made it all the way through the setup process.

- I got another new box yesterday. This one did go through the setup but now there are inconsistencies with the channels: Yesterday post-setup I had Fox News but not Comedy Central. Today after doing a system refresh I have Comedy Central but not Fox News (there's a generic error message about not being able to connect and to try again later

Please advise