Series X randomly doesn't pass HDMI signal to tv

That the Xbox Series X supports HDMI 2.1 doesn't mean your TV needs to support that too. You can user your old TV with the Series X for sure.

Update number 1, with a little more detail and the first failed solution attempt.

Hardware: Xbox series x, purchased brand new from retailer May 2023. LG television, 55 inch class 4k oled. Model OLED55C2PUA purchased new May 2023.

My issues include: Xbox powers up at 640 resolution on TV, x ox powers up and tv doesn't receive a signal from it, despite the TV activating when Xbox it turned on, signal drops out mid game with snow on screen like old school tv no channel snow, and when exiting a game to go back to the Xbox dashboard it loses signal. Unplugging and plugging back in the HDMI cable fixed the issue. Multiple cables and all HDMI ports were tried. Same conditions.

Attempt to fix 1: went with the optical HDMI cable mentioned earlier in this thread. This did not correct the disconnection/no signal issue. Therefore I can not recommend that as a solution.

HDMI repeater was suggested by another poster, that arrives today and will be trying that beginning tonight. The optical HDMI cable is not compatible with the repeater so I will be using top of the line HDMI cables. I will report back on the results.

For what it's worth, my series S has no problems connecting to the TV properly and does not lose signal.

The cable shouldn't be an issue...a HDMI cable capable of carrying a 4k signal should have no issues with HDR.

I assume you have tried the other 2 ports on your TV? I do say "other 2" knowing that if you have wall mounted your TV, the 3rd HDMI port basically becomes inaccessible due to how the TV was designed (The back of your TV is bizarrely desgined!)

I am not really an expert in either consoles or 4k TVs.....I do sometimes have the same thing happen where I lose the video signal but still have audio (happens on my Series X and my old One X) on my LG CX...but unplugging the HDMI from the TV and then pluggin it back in solves that.

I would check the console's video settings to make sure it doesn't have VRR (Variable Refresh Rate) switched on as your TV doesn't support it and it would cause issues but I suspect it won't be on

The Xbox One doesn't directly pass through the HDMI signal. It always "intercepts" everything coming in from the HDMI in port and processes it.

Since the original idea was to have TV and games "picture in picture", the Xbox takes the video signal, and processes it to be included with the TV app on the console and then outputs it via it's own video signal to the TV.

Since the original Xbox One isn't 4K capable, you will not get 4K from your cable box if you run it through the original Xbox One.

When you say 4K pass through, are you talking about a 4K source sending the TV signal to the Xbox and then to the TV? Or sending the Xbox1 X 4K signal to pass through a 4K receiver and then to the 4K TV?