No Sound - on all 4 Optik TVs

[wireless]

I have 4 Optik TV setups, all slightly different. Don't know what happened but I lost sound on all 4 setups. I have sound while using the Netflix app, my Chromecast etc. Just not any cable channels. So my cables are fine etc.
I've also done a hard reset on router. Still no change.

Looking for some other ideas before I call tech support....

Thanks!!


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