Screen Mirroring relies on being able to find Smart TVs on your home network and being able to communicate with your Smart TV. At the same time, your Smart TV must also be able to communicate with your Mac. Some router settings will block this communication. For everything to work smoothly, please apply the following router settings:
Ensure you have the latest firmware update for your router on the manufacturer’s website.
If you have a dual band router, use separate names for the 2.4GHz and 5Ghz network. Then make sure that both the Mac and the TV are on the same network. So: if the Mac is on 2.4Ghz, your TV should also be on 2.4Ghz. If the Mac is on 5Ghz, put your TV also on 5Ghz.
If you have a router with MAC address filtering, add the MAC address of your TV to the list of filtered devices.
Disable Access Point/Client isolation on your router.
Disable Wireless Isolation on your router.
Disable IGMP Proxy on your router.
Disable any Virtual Private Networks (VPNs) or proxy servers, on your router and/or computer.
Enable UPnP/Multicast on your router.
Enable IGMP on your router.