how can I connect an external hdd/flash storage thru usb-c port of sagemcom TMobile home internet gateway to be accessed wirelessly in home by wifi?

Routers can be connected to the gateway either wirelessly or by ethernet cable. Typically, ethernet is preferred. The USB port on the gateway can provide 5V power to a device, and it is often used by those who use a 5v cooling fan to help cool the gateway, when they are having overheating problems with their gateways.