My Apple TV stalls and I have high bandwidth

If you have a lot of interference then that is the issue. The distance between device and router would be a means of possible magnification. If the router and device are in different rooms then that is also a factor. The options would be to move the device to an area that isn’t as effected or use Ethernet.

Speedtest is one factor.

Make sure DNS is set to auto (settings - network)

If you are using Wifi then try ethernet

To see a current status of the network get a report from istumbler, netstumbler or similar. Look for signal strength, noise, nearby networks

Test on another network