D-Link 2660 USB 2.0 not working

I have a D-Link DIR-2660 A1 running LuCI openwrt-21.02 branch git-22.046.85957-59c3392.
This model has TWO USB ports, USB 2.0 on the rear and USB3.0 on the front. I am using the front port which is working fine, however, the rear USB port does not work / detect the external HDD I connect to it, while it works fine on USB 3.0