Recently there was a problem with connecting the phone to the computer and access the Internet. At the moment there is no possibility to connect a PC to the Internet via cable, so I decided to use a USB modem. In the settings of your samsung A5 met a problem: button usb modem just not available, a gray and doesn't react on clicking. The phone is connected, charging goes. With Xiaomi phone everything works perfect, but there is no way to use it on a regular basis, as it is not my phone. I will be very glad to answer, I hope, on the subject
Just give the Internet via Wi-Fi. Either in the phone settings change the connection mode via USB. A year ago Android phones with type-C, support OTG connection is almost not there - that is, until "is charging" cable nothing will be passed.