Check your Nano, if you have the one with CH340 usb chipset will not work for serial gateway. It will work if you use it for a node. Need to get another nano with FTDI chipset for serial gateway and it will work. I have the same problem and even try many different ways still won't work until I figure it out from the other post. You don't need to buy the one for $35 bucks, search on Ali.... you still find some sellers sell Nano with FTDI chipset for @ $7 bucks. Hope it help and save your time.