I am using a huawei  E3372 (megafon 4g+) stick in ncm/qmi mode. It works really great. But once in a while it stops working.

It sometimes loses connection and does not reconnect. I remedied the issue with the script at bottom of the wiki page https://wiki.openwrt.org/doc/recipes/ltedongle?s[]=ncm&s[]=network

But once in a while it gets locked completely. Even rebooting OpenWRT does not solve the issue. I have to go and physically remove and re-insert the device (btw do you know a way to simulate this remotely?)

The thing which bothers me is the "input wrong password many times" message. What in OpenWRT may be causing this? But this is not related to connectivity problem because I see it from the first moment I reboot the device.

Any ideas on what to look for or try when this happens again? Is there a way to reset the usb stick remotely? (tried at+cfun=1,0 and did not do anything but gave OK response).

After hard reset /dev/ttyUSB1 prints (I don't understand the RSSI change between failure condition and after removing putting back stick in same exact position)

^RSSI:28
^HCSQ:"LTE",64,55,166,22
^RSSI:27
^HCSQ:"LTE",62,57,181,28

When it locks below are what I see in the logs: (I am not sure if these appear from time to time under normal operation also)

Tue Mar 21 09:40:38 2017 kern.err kernel: [207642.735919] huawei_cdc_ncm 1-1.3.1:1.2 wwan0: kevent 12 may have been dropped
Tue Mar 21 09:40:38 2017 kern.err kernel: [207642.743970] huawei_cdc_ncm 1-1.3.1:1.2 wwan0: kevent 12 may have been dropped
Tue Mar 21 09:40:38 2017 kern.err kernel: [207642.751746] huawei_cdc_ncm 1-1.3.1:1.2 wwan0: kevent 12 may have been dropped
Tue Mar 21 09:40:38 2017 kern.err kernel: [207642.759564] huawei_cdc_ncm 1-1.3.1:1.2 wwan0: kevent 12 may have been dropped

I use miniocom to check the operation of the modem:

/dev/ttyUSB0 - Normal, responding to AT commands
/dev/ttyUSB1 - Normal, responding to AT + periodically prints:
...
^RSSI:17
^HCSQ:"LTE",43,50,156,30
^RSSI:15
^HCSQ:"LTE",39,46,156,30
^RSSI:17
^HCSQ:"LTE",42,48,161,30
^PLMNSELEINFO:0,4
^RSSI:99
^PLMNSELEINFO:1,1
^RSSI:99
^RSSI:16
^HCSQ:"LTE",41,45,151,24
^RSSI:17
^HCSQ:"LTE",42,48,161,28
^RSSI:19
^HCSQ:"LTE",47,49,156,20
...
/dev/ttyUSB2 - Periodically prints
[084759596ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0003 i0003 l0
[084759608ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0003 i0003 l0

Input wrong password many times, please reboot device
[084772889ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0003 i0001 l0
[084773383ms] U_NCM:(U_TRACE)ncm_vendor_notify():ncm_vendor_notify cmd=0
[084773390ms] U_NCM:(U_TRACE)ncm_vendor_notify():notify is busy, sending connect notify in work
[084773399ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0000 i0001 l0
[084773406ms] U_NCM:(U_TRACE)ncm_notify_work():send notify 1 in work
[084776415ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0003 i0001 l0
[084776422ms] U_ACM:(U_ERROR)acm_setup():acm ttyGS0 req21.22 v0000 i0001 l0

(Last edited by yurtesen on 21 Mar 2017, 09:01)