Facing TV Problems? Ask a TV Technician.
Hello, First- your Nighthawk router has nothing to do with your Comcast picture- completely different signals. So, if you're referring to the picture quality from your Comcast cable box specifically, then you will want to look at the box as being the root cause of the problem. If it appears the resolution is bad, then I would suggest a reboot of your Comcast box.
Shut the TV off, then pull the power cord out from the Comcast box out of the outlet (unplug it from power).
Then disconnect and reconnect the HDMI cable between the two on BOTH ends- making sure it is secure.
Plug the Cable Box back in and give it 3 minutes to reboot, then turn the TV on.
Let me know if the picture quality still appears poor and if so- I will need the BRAND and MODEL number off of the front of the Comcast cable box.
Please read my reply posted above and try those steps. Then let me know what happens.
Did you try the cable box reboot yet? The reason I ask is that the cable box can drop resolution down to 480 or 720 without warning and a reboot can put it back to 1080?
Do you need further assistance with this?
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