LTE Huawei E3372 stopped working

Hello expert,

My router Linksys wrt16nl is running OpenWRT 19.07.2 r10947-65030d81f3 is using USB LTE modem Hyuawei E3372. The configuration is up and running without canges for almost a year without any issues.

Today out of sudden the connection to the Internet got broken. Checking the LTE interface in Luci it said "Network device is not present". I have unplugged the device from the router and connected it to Windows 10 PC and connected to the Internet using the provided driver - it connected succesfuly - modem should be OK.

The configuration is following:

config interface 'LTE'
        option proto 'ncm'
        option ifname 'wwan0'
        option apn 'internet'
        option ipv6 'auto'
        option dialnumber '*99#'
        option pdptype 'IP'
        option delay '30'
        option device '/dev/ttyUSB0'

If I change the device to /dev/ttyUSB1, the error is gone a virtual interface LTE_4 appears (as when it worked) and there are even some TX packets in LTE Interface. But no luck with the internet.

Reading the instructions https://openwrt.org/docs/guide-user/network/wan/wwan/ethernetoverusb_ncm I came to the statement " You need to switch modem to provide native NCM interface instead of Modem interface." I guess that this might be the problem but I do not know how to fix it.

Can anyone help?

Please tell us the hardware version like E3372h-??? and firmware version used in your modem.
Show the output of cat /sys/kernel/debug/usb/devices

I am not sure about the version. ATI says

ati
Manufacturer: huawei
Model: E3372
Revision: 21.328.62.00.445

cat /sys/kernel/debug/usb/devices says:

P:  Vendor=12d1 ProdID=1506 Rev= 1.02
S:  Manufacturer=HUAWEI_MOBILE
S:  Product=HUAWEI_MOBILE
C:* #Ifs= 5 Cfg#= 1 Atr=80 MxPwr=  2mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=02 Prot=12 Driver=option
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=02 Prot=01 Driver=option
E:  Ad=84(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:  If#= 2 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=02 Prot=16 Driver=huawei_cdc_ncm
E:  Ad=86(I) Atr=03(Int.) MxPS=  16 Ivl=2ms
I:* If#= 2 Alt= 1 #EPs= 3 Cls=ff(vend.) Sub=02 Prot=16 Driver=huawei_cdc_ncm
E:  Ad=86(I) Atr=03(Int.) MxPS=  16 Ivl=2ms
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=(none)
E:  Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=125us
I:* If#= 4 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=(none)
E:  Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=125us

Sorry for replying faster than thinking. I have added the log when the stick was not plugged in. Now is the output reply corrected.

You have the old good E3372h in the right configuration and with the proper firmware.
Just configure it according to the instructions you mentioned - remove dialnumber, use device '/dev/cdc-wdm0'

In the meanwhile I did se several restarts and repluging and now it works again without any configuration changes.

I guess there is some hardware issue :frowning: