Airplay to LG Smart TV

My boyfriend and I both have MacBook Pros. He's still using Catalina and has no issues.
I updated to Big Sur 11.2.2 (20D80) and I cannot use the airplay feature on our LG smart TV (UN7240PVG).

One of a few things happen:

1. I go to Display under System preferences and select the TV. It selects it for a moment and the selection reverts back to the "Off" option. Then a pop-up appears saying the connection fails.

2. Sometimes it does connect through the above way, but it is skipping and the sound pauses every few seconds and is not a pleasant viewing experience.

3. I open QuickTime player with a movie and use the AirPlay icon from there and select the TV. I still see the play/pause action menu, but the rest of the player goes black and the TV is stuck on the AirPlay settings menu.

For option 3 I go between resetting the device in AirPlay to forget the 1 time passcode (which only sometimes will work to give me a new code), asking for a password for each connection, or a code each time a device is connected. Nothing works. Even when I do manage to be given a passcode the TV stays on the AirPlay setting screen and the video player on the computer stays black.

Quite annoying! Please please please fix!

I've tried the fire wall setting mentioned here a few times, but this didn't work for me.

Anyone else found a fix for something similar happening?