RPi-2 Arch multiple modems

[John Whitmore <arigead gmail com>]

Hello all,

I had a Raspberry Pi running Arch with two USB LTE Modems on two differet
Network operators. This was all working perfectly but suddenly crashed mid
week. Instead of repairing that old system, I still have it and can go back to
it, but I decided that I'd grab a new SD card and install the latest and
greatest.

This is where the problem is I create my two LTE network connections and
sometimes the network manager seems to be attempting to create network
connections on the wrong modem. 

When I pulled one modem I powered up and got an IP Address from one connection
but when I couldn't ping anything I had a look in the network manager and it's
connected a "Three" operator connection on a "Vodafone" SIM. This used to work
perfectly.

BTW as both my modems are exactly the same model I can't distinguish them with
udev rules.

NetworkManager  1.0.8-1
ModemManager    1.4.12-1
ModemManager-qt 5.16.0-1