2018 Mini with Sonnett Breakaway Puck and AppleTV application issue

[N9JIG]

I have been using a Sonnett Breakway Puck with an RX560 for a year on and off. I had reduced my footprint back to two monitors so the Puck was removed and not used for a few months. I had no problems with it, with up to 4 of the Asus VA32AQ monitors while I was using it.

This week I decided to put it back into service and reconnected it to the computer. Everything went well except that when I watch a TV show on AppleTV where it breaks up, rasterizes and pixelates. With the same monitors connected directly to the Mac (one via the HDMI and the other thru a TB3-DP adapter) the playback is perfect.

I tried various settings within the AppleTV application and no improvement there. AppleTV worked fine before, no video issues.

I then removed the Puck and everything worked fine again. I tried replacing the TB3 cable as well as the DP and HDMI cables and got similar results. I get the same issue on either monitor.

I have no issues playing back video at high resolutions in Netflix, Hulu or YouTube via a browser. The same shows work fine on both of my AppleTV boxes via WiFi.

Any ideas?


System:
Mac Mini, 2018, 32GB RAM, 3.2 GHz 6-Core I7, UHD 630 internal graphics with OS 11.2.3
2 Asus VA32AQ displays at 2560x1440, 60 Hz.
Internet connection is running between 850 and 875 Mbps with a 3 ms ping. Ethernet used to connect to the switch.

 

[N9JIG]

Things get weirder...

I have found that the issue only occurs when I am running Firefox on one screen while watching AppleTV on another. As pages load in Firefox the TV show rasterizes or shows static and hopping. For instance as I scroll thru Facebook or read these forums and data passes to the browser it interfers with AppleTV. Chrome, Safari and Opera do not seem to affect things.

I wonder if there is something between AppleTV and Firefox that causes one to monopolize thru-put? I tried disconnecting the Ethernet cable and tried it via the WiFi with the same results.

 

[N9JIG]

In working with Sonnet support over the last couple weeks they have not been able to replicate the issue. Since it was occurring on both my MBP and the Mini I have to assume it is an issue with the eGPU or (unlikely) my internet connection.

Regardless, after updating both computers to the latest MacOS 11.3.1 the issue seems to have disappeared. I have to assume that it was some sort of imcompatibility between the OS, AppleTV and the eGPU.