I recently ordered two Raspberry Pi 4 (4 GB) boards, two fan SHIMs, an Ubercorn, and a Unicorn HAT HD. Each board has a fan SHIM, the same model of power supply and microSD card, and each has one of the HATs. Both are running Buster.
The unit with the Ubercorn works perfectly fine, but the one with the Unicorn HAT HD works (mostly) fine until I open Chromium. Upon doing so, any network activity will hang. If I close Chromium quickly enough, traffic continues, but if I leave Chromium open for more than a few seconds, network connectivity does not return. Some tampering might make it return, but I usually have to reboot it. I feel like I had tried another browser once and experienced the problem, but I couldn’t reproduce that; further testing with Firefox and Epiphany resulted in no traffic problems — only Chromium caused the network connectivity to halt.
I’ve wiped it repeatedly, installed Raspbian through different sources, but the problem continued.
I swapped the microSD card from the Ubercorn into the one with the Unicorn HAT HD, and it experienced the same problem, so at that point, I knew that it was a hardware issue.
I removed the Unicorn HAT HD, and it works with no problems when Chromium is opened. Putting the HAT back on, the problem returned.
From this, I’m not entirely sure what the issue could be. I suppose it could be a faulty Unicorn HAT HD, as I previously purchased a faulty Unicorn HAT (at least I assume that it was faulty; wasn’t able to figure out what was causing the problem), and my other Unicorn HATs HD work fine on my 3B+ units. The only thing that makes me wonder if it might be problem with the RPi4 itself is that my keyboard/mouse USB dongle doesn’t function in the bottom USB 2.0 port; other devices work in that port, and the dongle works in other ports, but just not that dongle in that port, and I have no idea why.
So, in summary, removal of the HAT avoids the problem, but with that strange behaviour along with the dongle port pickiness, I’m not sure what the cause might be.
I have not yet tried swapping the HATs around to see if the unit that had the Ubercorn now experiences the problem, but if there’s any chance that a faulty HAT may have caused damage to the RPi4 that may have resulted in the strange USB behaviour, then I wouldn’t want to risk the other RPi4. Hence, I figured that I should ask for help here first.
Thanks for reading!