I've noticed a similar question closed as a duplicate of this question about too many USB devices in general. This is not the same thing, as it applies only to the Pi4.
The background here is some time back we needed a way to scan bar codes on our production floor. We found that the Pi3B+ was well suited to the task. We put the device wireless dongles on a powered USB hub and a Python script running in PiOS grabs the input data and puts it into a database for later use (the DB is cleaned every day, so it's not a full drive issue either). We have several setups doing this without issue.
A couple of years ago we began to expand to other off-site areas and we needed new setups, which meant buying new Pi devices. At that time, I bought a Pi4 to keep up with the changing hardware and moved to update to the latest PiOS (Buster in this case). Upon installing the Pi with all the scanners hooked up, however, I found that only a fraction of them worked. The magic number here seems to be around 7 to 8 devices. Beyond that, the USB controller will freeze up and/or not recognize the new devices until I remove them below the threshold. Replacing the USB hub has no effect (tried several, including different brands), nor do I have too many devices on the hub. Swapping the 4 out for a 3B+ fixes the problem.
I've found others who mention the same problem, but their fix doesn't work (eeprom is up to date and has not been updated upstream since 2020).
Up until now, the 3B+ was easy to source so I figured I could limp this along until the Pi4 got fixed, but that luxury has now ended. Is there any indication of what else could be wrong, or how I could fix it? Is it possibly fixed in Bullseye?
