I just activated the X1 TV cable box on the main tv. I now have the 340 error code on my second tv. I have the little cable box on the second tv. I went on line to activate. I was informed that there was a problem and i needed to call comcast. I tried that and i keep getting disconnected.
Quite welcome ! Good luck !
How can i fixed code 340?
Did you see the link that I provided above ?