See attached. These changes keep nusb/serial from attempting to use an RNDIS endpoint. Without this patch, nusb/serial will generate an error like: nusb/serial: getdev: '/dev/usb/ep17.0/data' device or object already in use when an RNDIS endpoint has already been found (e.g., a pinephone usb tether). I had unfortunately overlooked this part when I submitting my previous patch for nusb/ether. Additionally, if there is no ethernet on boot, don't attempt to look for an address. The last bit is just updating a comment to match the code.