I'm presently using 3.1, 3.5, 3.9 and 4.1 on a regular router via the same cnet.device driver with built in modem no problem.
One thing I did at the router end was to reserve a fixed local IP address for all the permanently attached devices (PC, A1, A1200, printer, IPcam and so on) and leave the DHCP server to dole out new addresses only for transient connections.
