Uverse WAP configured on personal router

So I have ATT internet 100, as well as Uverse TV with wirelessly connected receiver boxes.

From the beginning, ive been using an Asus router, first an ac68 and now an ax92u( both on mesh)

I disabled the internal wifi of the ATT modem, and have the asus connected on the ATT in passthrough mode with firewall settings on the ATT modem completely disabled.

Never have any issues with the internet, or wifi, 

But I was never successfully able to get the Uverse WAP stably connected through the asus router. Meaning I was able to get it connected, and get a picture from the receiver output onto a TV, but it lags like watching prn on a junky slow site. (It's all choppy) and from what I can remember from the last I attempted it, the remote didn't function right either like rewind etc. 

After a big headache I finally just gave up on it, and left the Uverse WAP connected directly to the ATT gateway.

When it works, it's fine, but the connection gets disconnected quite frequently.

Like multi times a day, where I gotta go to the WAP and re-connect the wireless recrivers to the transmitter box.

What is the correct way to get the uverse multicadt traffic working through the Asus router? 

I feel like the connection will be more stable that way, (once its properly configured)

and if not, then itll oprn up the option of connecting the WAP transmitter to a mesh router located closer to the uverse receiver