My TV is showing up in the Devices Section. However, the screen mirroring does not start on my TV.
This happens when your TV connected to the same router as your Mac, but on a different subnet. Let’s first explain how this works. Your Mac and your TV both have (different) IP addresses. They look like this: 192.168.10.3 for instance. The structure is like aaa.bbb.ccc.ddd (where as every block is a number between 0 and 255.
If your Mac is on the same subnet as your TV, the first three sets of digits (aaa.bbb.ccc) should be 100% identical. Only the last set of digits (ddd) should be different. If this is not the case, then you should either put your Mac on the same subnet as your TV, or your TV on the same subnet as your Mac. Most of the time, this is just a matter of connecting your Mac to the same Access Point as your TV.