Bought Refurb SBG6580 for $64 year back from eBay and it stopped worked in few months. Then bought Refurb from Walmart with 1 year protection plan.
It still works great.
Unfortunately this doesn’t have USB Port to create WiFi storage. Note SBG6580 has 2 models. One with USB and another without USB. I searched everywhere but couldn’t the USB port model.
If you check the back panel, there’s a usb port.
I think venkatx5 meant USB Type A Female connector to plug in a hard drive or a usb flash drive.