Hi Matti,

 > -------------------------
> usbserial:
> --------------------------
> usbserial: USB Serial support registered for GSM modem (1-port)
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1
> usb 2-1: GSM modem (1-port) converter now attached to ttyUSB2
>

Are you sure the ttys are handled by the 'usbserial' module and not 
'option'?  If they really are, then you might need to update 
plugins/udevng.c appropriately.

Right now I see the following in the vendor_list[] table:
         { "huawei",     "option",       "201e"          },
         { "huawei",     "cdc_wdm",      "12d1"          },
         { "huawei",     "cdc_ether",    "12d1"          },
         { "huawei",     "qmi_wwan",     "12d1"          },
         { "huawei",     "option",       "12d1"          },

You probably also need to add an entry for cdc_ncm.  See the recent 
patch adding similar support for mbm:
git show b04fabcda34b6433209bacab32b78a95b1c11b3e

I'd start with adding the cdc_ncm entry to vendor_list[] table and see 
if that makes things work.

Regards,
-Denis