I'm wondering if anyone has seen this issue when trying to connect a 3g dongle (I have tried ZTE MF112  and Huawei K3520) to a Lantiq router. I have seen the same issue with both tp-w8970 and BThomehub 2B.

My config looks like

config interface 'wan2'
        option ifname '3g-wan2'
        option device '/dev/ttyUSB2'
        option apn 'mbb.voiamo.net'
        option service 'umts'
        option proto '3g'
        option dns '208.67.222.222 208.67.220.220'
        option metric '30'
        option peerdns '0'

The dongle fails to connect; the connection gets stuck on

 gcom -d /dev/ttyUSB2 -s /etc/gcom/getcardinfo.gcom

The process cannot be killed while the dongle is present and it has to be disconnected.

I have also wdr3600 (ar71xx) and the same config works flawlessly with both dongles.

(Last edited by dziny on 8 Mar 2015, 18:30)

Is  /dev/ttyUSB2 created when you plug in the modem?  Check dmesg for USB related messages.  You may need a kernel driver such as kmod-usb-acm (for old models), kmod-usb-serial-wwan, or one of the vendor specific ones like kmod-usb-serial-option.  Do a lsmod on the system that works and see which modules are in use.

Usually the modem will have several ports, but number 0 is the one to use to make a ppp call and connect to the Internet.

(Last edited by mk24 on 8 Mar 2015, 21:28)

I have checks dmesg and all ports /dev/ttyUSB0-/dev/ttyUSB2 are created when the dongle is plugged. It looks normal. So that's is definitely not an issue. I have the same kernel modules installed on w8970 and wdr3600 but it just hangs on Lantiq (w8970). Concerning the port number, MF112 uses /dev/ttyUSB2 (again works like that fine on wdr36000), my other dongle K3620 uses /dev/ttyUSB0 for the ppp.

I have this problem too on a Netgear DGN3500. I found this bug report (https://dev.openwrt.org/ticket/18424), which was closed, but I've just reopened it.

I do not see this issue on w8970 or another lantiq target (Bthomehub 5A) on DD trunk (self compiled). I have also used w8970 with "eko" build of CC and the 3g modem worked reliably. So it's a strange issue that went away for me when I moved from BB.

(Last edited by dziny on 15 May 2016, 20:16)