New Macbook and New Apple TV 4K device will not connect to Ethernet (IP address is self-assigned as 169.254.x.y)

If not caused by cables or switches or other connectors, then a self-assigned IP may point to DHCP issues at the router, i.e. a software malfunction, even if other devices connect fine. Have you tried restarting the router?

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Ethernet should give a good clean signal for at least 100m (300+ ft), unless it gets heavy interference from a nearby source (e.g. electrical wiring, radio transmitters). Powered switches would boost a signal between two ethernet segments, to allow even longer total lengths. Use ‘Cat 5e’ graded cables or better for gigabit. Shielded cables have an extra layer on the outside to help keep interference out more, if needed.

A specific port on an ethernet switch can be a weak point. Try changing which device connects to which port, to find out if any specific port gives trouble. If a device on e.g. port 3 gets great speeds, then try Apple TV on that port instead.

How long is the cable including any in-wall wiring (distance port to AP/switch port)?

So the cable is effectively 36.5 feet = over 11m which is too long by Apple standards. I would stick a switch in front of the wall, should fix.

You’re referring to the terminating side, not originating. Stick a switch where the 2m cable ends before connecting it to the wall socket, should fix.

Looks like the inWall cabling to your Apple device room is defective. Can the MacBook ping the router? What OS versions are running on the MacBook and Apple TV? Can they connect from the rooms where they”distant” devices are? Long shot: Try 1m from device to switch instead of 2.

Great, thanks for updating. Yes, it’s true that Apple devices frown upon long cable lengths - it’s most likely by design built into their hardware. Doesn’t matter what the cable specs say on the box - anything longer than 1m is inviting trouble.