设备接入ec25模块，使用quectel-CM进行拨号上网，连接网络是正常的，但是很容易就出现erro然后退出。
遇到的erro是：
[02-22_06:59:23:592] QmiWwanThread poll err/hup/inval
[02-22_06:59:23:592] poll fd = 7, events = 0x0018
[02-22_06:59:23:592] QmiWwanThread exit
[02-22_06:59:23:593] ifconfig wwan0 0.0.0.0
SIOCSIFADDR: No such device
wwan0: ERROR while getting interface flags: No such device
[02-22_06:59:30:088] ifconfig wwan0 down
wwan0: ERROR while getting interface flags: No such device
[02-22_06:59:30:178] qmi_main exit
下面是完整的日志：
root@240057:~# quectel-CM
[02-22_06:57:54:069] Quectel_QConnectManager_Linux_V1.6.0.24
[02-22_06:57:54:072] Find /sys/bus/usb/devices/2-1 idVendor=0x2c7c idProduct=0x125, bus=0x002, dev=0x00b
[02-22_06:57:54:075] Auto find qmichannel = /dev/cdc-wdm0
[02-22_06:57:54:075] Auto find usbnet_adapter = wwan0
[02-22_06:57:54:075] netcard driver = qmi_wwan, driver version = 5.15.43-dra
[02-22_06:57:54:076] Modem works in QMI mode
[02-22_06:57:54:153] cdc_wdm_fd = 7
[02-22_06:57:54:251] Get clientWDS = 20
[02-22_06:57:54:281] Get clientDMS = 1
[02-22_06:57:54:313] Get clientNAS = 4
[02-22_06:57:54:345] Get clientUIM = 1
[02-22_06:57:54:379] Get clientWDA = 1
[02-22_06:57:54:410] requestBaseBandVersion EC25EFAR06A08M4G
[02-22_06:57:54:539] requestGetSIMStatus SIMStatus: SIM_READY
[02-22_06:57:54:570] requestGetProfile[1] 3gnet///0
[02-22_06:57:54:602] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:57:54:634] requestQueryDataCall IPv4ConnectionStatus: DISCONNECTED
[02-22_06:57:54:634] ifconfig wwan0 0.0.0.0
[02-22_06:57:54:644] ifconfig wwan0 down
[02-22_06:57:54:698] requestSetupDataCall WdsConnectionIPv4Handle: 0x872980c0
[02-22_06:57:54:826] ifconfig wwan0 up
[02-22_06:57:54:836] busybox udhcpc -f -n -q -t 5 -i wwan0
udhcpc: started, v1.30.1
udhcpc: sending discover
udhcpc: sending discover
udhcpc: sending discover
udhcpc: sending discover
udhcpc: sending discover
udhcpc: no lease, failing
[02-22_06:58:10:224] File:ql_raw_ip_mode_check Line:136 udhcpc fail to get ip address, try next:
[02-22_06:58:10:224] ifconfig wwan0 down
[02-22_06:58:10:237] echo Y > /sys/class/net/wwan0/qmi/raw_ip
[02-22_06:58:10:238] ifconfig wwan0 up
[02-22_06:58:10:256] busybox udhcpc -f -n -q -t 5 -i wwan0
udhcpc: started, v1.30.1
udhcpc: sending discover
udhcpc: sending select for 10.4.9.102
udhcpc: lease of 10.4.9.102 obtained, lease time 7200
[02-22_06:58:13:067] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:14:123] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:15:083] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:17:035] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:23:403] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:24:779] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:26:283] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:27:659] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:29:740] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:29:772] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:33:419] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:44:107] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:45:835] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:48:204] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:49:067] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:51:083] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:53:355] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:55:467] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:56:939] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:58:58:859] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:00:619] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:01:739] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:03:212] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:04:779] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:07:244] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:08:395] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:11:660] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:14:252] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:18:092] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:19:563] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:20:555] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:21:867] requestRegistrationState2 MCC: 460, MNC: 1, PS: Attached, DataCap: LTE
[02-22_06:59:23:592] QmiWwanThread poll err/hup/inval
[02-22_06:59:23:592] poll fd = 7, events = 0x0018
[02-22_06:59:23:592] QmiWwanThread exit
[02-22_06:59:23:593] ifconfig wwan0 0.0.0.0
SIOCSIFADDR: No such device
wwan0: ERROR while getting interface flags: No such device
[02-22_06:59:30:088] ifconfig wwan0 down
wwan0: ERROR while getting interface flags: No such device
[02-22_06:59:30:178] qmi_main exit