ZTE MF823 USB Ethernet Dongle on RPi-2/Arch/LXDE

[John Whitmore <arigead gmail com>]

Been on a few times between this list and the ModemManager. I was hoping to
setup a system where I could build some intelligence behind two USB 4G Dongles
and jump between connections depending on signal strength.

My second Dongle has stopped that, as it don't report as a Modem device and
instead uses Ethernet over USB. This all works out of the box on my OpenSUSE
Laptop but the RPi-2 doesn't work.

On the laptop "usb-devices" is giving me:

T:  Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  5 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=19d2 ProdID=1403 Rev=50.09
S:  Manufacturer=ZTE,Incorporated
S:  Product=ZTE Technologies MSM
S:  SerialNumber=MF8230ZTED010000CP261718SKYDWQ5II0PESHF3BW707_8C64&&&&&&&&&&&&&0
C:  #Ifs= 3 Cfg#= 1 Atr=a0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=02 Prot=ff Driver=rndis_host
I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host
I:  If#= 2 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage


So it's using the "rndis_host" driver. If I grep for that driver in lsmod I
get:

john bamboo:> lsmod | grep "host"
rndis_host             14513  1 rndis_wlan
cdc_ether              14361  1 rndis_host
usbnet                 43864  3 rndis_host,rndis_wlan,cdc_ether


The laptop also gives me an extra network device:

ens3u1    Link encap:Ethernet  HWaddr 36:4B:50:B7:EF:9E  
          inet addr:192.168.0.194  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::344b:50ff:feb7:ef9e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:47 errors:0 dropped:0 overruns:0 frame:0
          TX packets:83 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3502 (3.4 Kb)  TX bytes:21953 (21.4 Kb)

Now the RPi-2 On the other hand when I do "usb-devices"  shows that where the
OpenSUSE uses "rndis_host" the RPi-2 uses "cdc_ether". In addition there's no
mention of the additional modules mentioned by lsmod in OpenSUSE (rndis_host,
rndis_wlan, usbnet)

So should I be black listing cdc_ether? I can't see that I can do that as that
driver is used by the working OpenSUSE but it's just one of a number of
drivers used in the device. Any ideas would be gratefully received.

John