Info: USB Ports can be a source of problems with USB WiFi adapters

[morrownr]

Hello all,

I've been helping users of USB WiFi adapters for some years now and I have noticed that problems are generally first blamed on the driver in use. I get that. However, our USB WiFi adapters depend on support from multiple stacks (USB and WiFi) as well as hardware that needs to be compatible. As an example, here is a post in a Debian forum:

https://forums.debian.net/viewtopic.php?t=159402

Note that this user was able to stabilize his USB WiFi adapter after changing BIOS settings and switching to a different port.

What I have noticed over the last few years that contribute to problems for our adapters:

• USB3 gen2 ports can be problematic, especially with older adapters such as the one in the forum post above. The mt7612u is a favorite chip among Linux users but it was released about 10 years ago and could not be tested with modern USB3 gen2 ports because they did not exist at the time.

• USB ports wear over time and various things can happen if contacts are not solid.

• It is always a good idea to try a different USB port if you have a problem.

• There are problematic USB3 hub chips and problematic USB drivers.

• There are USB BIOS settings that can cause problems.

• When in doubt, if you have a USB2 port, give it a try. USB2 is simply more stable than USB3 and in most cases, it is fast enough for the use case.

• Powered USB hubs and extension cables can be problematic. Plug the adapter directly into a port to test if this could be a problem.

• Some USB subsystems to do not provide spec power leaving you in a low power condition. I am looking at you RasPi.

I hope this helps and I am going to pin this issue. Feel free to add your own ideas and experiences.

@morrownr

[fhteagle]

Agreed with all of the above, and I'll add more detail that could apply to a couple of the cases on your list:

If you're not getting the speed test results you are expecting, it may be that your USB adapter has fallen back to USB2 speeds despite both host and device being USB3+ capable. To check this, use lsusb -tv (not installed by default in all distros). Look for a speed to the right of your device, something like "480M" or "5000M". Expect to maybe get 60% of whatever that number says as a cap on actual throughout. For example, I have a USB Ethernet NIC that fails down to 480M speeds, and I get a very solid 330Mbps on that NIC.