My preference has been to set up USB dongles in Ethernet mode so they appear as an Ethernet interface, because I suspected that a USB Ethernet interface would be more efficient for Linux than a ppp over ttyUSBx interface. I've always found the wwanX interface more reliable. I have a ZTE MF821 USB dongle that doesn't seem to present such an interface though, or at least it doesn't when I plug it into an OpenWRT router. I can't seem to find any data on which is better though. Does anyone have any evidence or opinion on if it matters? Thanks James