Weird USB behaviour on MacBook Pro 15" (Mid 2015): USB 2.0 works, but USB 3.0 doesnt.

[Alexomaster]

I recently discovered that my right USB port somehow only supports USB 2.0, when I connect a 3.0 device it is not even recognized.

I made a little experiment: USB 3.0 flash drive connected to the left USB port: just works. Then a USB 2.0 extension plugged between the drive and the mac: works too, only slower. On the right port with USB 2.0 extension: no problem either. But if I connect the flash drive directly, it is not recognized. The drive is also not displayed in the system report.

How can it be that not even a USB 2.0 connection can be established?
Has anyone ever heard of this problem? It's a hardware problem, isn't it?

 

[Fishrrman]

Is this a USB flashdrive that' giving you the problem?

Do you have anything else with which to test the port in question?

The "problem" could be limited to that particular flashdrive you have...

 

[Alexomaster]

Is this a USB flashdrive that' giving you the problem?

Do you have anything else with which to test the port in question?

The "problem" could be limited to that particular flashdrive you have...

I'm sorry, I completely forgot to write that the same behavior occurs with an external USB Type-c hard drive.
I even tried an Android smartphone that supports USB 3.0. I can access the data on the smartphone via a USB 2.0 charging cable, but not with a USB 3.0 cable. It doesn't even show that a device is connected. Charging works however, so power doesn't seem to be the problem.
I also tested it on the left port, but everything works fine there.

 

[Alexomaster]

Ok, I solved the problem myself. Now the right USB port is fully functional again.
I just flushed the USB port with a lot of rubbing alcohol. Apparently it was just filthy.