I got one firmware which I don't like but there is one interestiong option named ENABLE USB 2.0 ONLY MODE. What packages do I need to install to have this utility?
You could try removing kmod-usb3, so then the only USB driver is USB2.
In that case my router doesn't see my flash which is 3.0. The utility I'm looking for allows to down USB 3.0 to 2.0 but the router sees usb 3.0 after that, just works with 3.0 like it's 2.0. You see the difference 
You could use a USB 2 extension cable.