Horizontal lines on my VIZIO TV

[Bsweetone]

over the past several days I've had horizontal lines going from bottom to the top of my VIZIO tv screen (TV is less than 2 years old).  Prior to this, the TV signal would flip flop between HDMI and "normal".  Doesn't matter if I'm watching comcast channels or other streaming apps.  I've replaced all cables and reset the system multiple times.  I just found out that the modem I have (from comcast) is no longer supported so I've ordered an more up to date one from comcast.  My question is does this sound like an issue with comcast equipment or the TV itself.  Any help would be appreciated.  Thank you.

[CCAndrew]

TV, do you have something else with an HDMI connection? You already proved it when you said the tv’s streaming apps do it and the cable box has nothing to do with the apps, cable box has no control over the inputs, and your modem has nothing to do with your tv controls

[Bsweetone]

No, I have no other HDMI connections.  I was hoping there would be a less expensive solution.  But thank you for the help.  Looks like I'm looking for a new TV today!  Anyone have a brand preference? I've had sony and vizio.  I just need a smart tv, no other bells or whistles needed.

[CCAndrew]

Try contacting Vizio, maybe they could help with a possible fix if there is one