Cutting holes is almost always the best solution. When that is not possible powerline adapters are usually the next best thing. Here is the one I recommend.

You’ll also need some extra ethernet cables on each end or the connection.

If you are out of ports in your router you’ll also need a switch.

TP-Link TL-SG1005D 5-Port Unmanaged Gigabit Desktop Switch
List Price: $21.97
Price: $16.99
You Save: $4.98
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