

I don’t think anyone has mentioned this but HDMI is just Cat-6 with a fancy hat. You can run cat-6 cabling through your attic, down the walls, etc., as if you were setting up a standard Ethernet run. Then, slap some rj-45 to hdmi adapters on each, and voila! Or you could just put proper hdmi heads on the cable ends and skip the adapters.
EDIT: Amazon product link with diagrams.















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