使用 quectel-CM 连接4G网络，成功以后会断掉，输出日志如下
[03-20_22:41:55:832] Quectel_QConnectManager_Linux_V1.6.0.24
[03-20_22:41:55:834] Find /sys/bus/usb/devices/1-1 idVendor=0x2c7c idProduct=0x6002, bus=0x001
[03-20_22:41:55:835] Auto find qmichannel = /dev/ttyUSB1
[03-20_22:41:55:835] Auto find usbnet_adapter = usb0
[03-20_22:41:55:835] netcard driver = cdc_ether, driver version = 22-Aug-2005
[03-20_22:41:55:835] Modem works in ECM_RNDIS_NCM mode
[03-20_22:41:55:849] /proc/652/fd/9 → /dev/ttyUSB1
[03-20_22:41:55:849] /proc/652/exe → /usr/sbin/ModemManager
[03-20_22:41:58:874] atc_fd = 7
[03-20_22:41:58:875] AT> ATE0Q0V1
[03-20_22:41:58:877] AT< ATE0Q0V1
[03-20_22:41:58:878] AT< OK
[03-20_22:41:59:878] AT> AT+QCFG=“NAT”,1
[03-20_22:41:59:882] AT< OK
[03-20_22:41:59:882] AT> AT+QCFG=“usbnet”
[03-20_22:41:59:885] AT< +QCFG: “usbnet”,1
[03-20_22:41:59:885] AT< OK
[03-20_22:41:59:885] AT> AT+QNETDEVCTL=?
[03-20_22:41:59:887] AT< +QNETDEVCTL: (0-3),(1-15),(0-1)
[03-20_22:41:59:887] AT< OK
[03-20_22:41:59:887] AT> AT+CGREG=2
[03-20_22:41:59:889] AT< OK
[03-20_22:41:59:889] AT> AT+QNETDEVSTATUS=?
[03-20_22:41:59:891] AT< ERROR
[03-20_22:41:59:891] AT> AT+CGMR
[03-20_22:41:59:893] AT< EC800MCNLFR06A03M04
[03-20_22:41:59:893] AT< OK
[03-20_22:41:59:893] AT> AT+CPIN?
[03-20_22:41:59:895] AT< +CPIN: READY
[03-20_22:41:59:895] AT< OK
[03-20_22:41:59:895] AT> AT+QCCID
[03-20_22:41:59:898] AT< +QCCID: 89860019221940763090
[03-20_22:41:59:898] AT< OK
[03-20_22:41:59:898] requestGetICCID 89860019221940763090
[03-20_22:41:59:898] AT> AT+CIMI
[03-20_22:41:59:900] AT< 460028924403090
[03-20_22:41:59:900] AT< OK
[03-20_22:41:59:900] requestGetIMSI 460028924403090
[03-20_22:41:59:901] AT> AT+COPS=3,0;+COPS?;+COPS=3,1;+COPS?;+COPS=3,2;+COPS?
[03-20_22:41:59:904] AT< +COPS: 0,0,“CHINA MOBILE”,7
[03-20_22:41:59:904] AT< +COPS: 0,1,“CMCC”,7
[03-20_22:41:59:904] AT< +COPS: 0,2,“46000”,7
[03-20_22:41:59:904] AT< OK
[03-20_22:41:59:905] AT> AT+QNETDEVCTL?
[03-20_22:41:59:907] AT< +QNETDEVCTL: 0,0,0,0
[03-20_22:41:59:907] AT< OK
[03-20_22:41:59:907] requestQueryDataCall err=0, call_state=1
[03-20_22:41:59:907] ifconfig usb0 0.0.0.0
[03-20_22:41:59:916] ifconfig usb0 down
[03-20_22:41:59:933] AT> AT+CGACT?
[03-20_22:41:59:937] AT< +CGACT: 1,1
[03-20_22:41:59:937] AT< OK
[03-20_22:41:59:937] AT> AT+QNETDEVCTL=1,1,1
[03-20_22:41:59:941] AT< OK
[03-20_22:41:59:941] requestSetupDataCall err=0
[03-20_22:41:59:941] AT> AT+CGPADDR=1
[03-20_22:41:59:948] AT< +CGPADDR: 1,“10.33.63.96”,"::0:0:0:0:0:0:0"
[03-20_22:41:59:948] AT< OK
[03-20_22:41:59:949] requestGetIPAddress 10.33.63.96
[03-20_22:41:59:949] requestGetIPAddress err=0
[03-20_22:41:59:949] AT> AT+QNETDEVCTL?
[03-20_22:41:59:949] AT< +QNETDEVSTATUS: 1
[03-20_22:41:59:951] AT< +QNETDEVCTL: 1,1,1,1
[03-20_22:41:59:951] AT< OK
[03-20_22:41:59:952] AT> AT+CGACT?
[03-20_22:41:59:955] AT< +CGACT: 1,1
[03-20_22:41:59:956] AT< OK
[03-20_22:41:59:956] requestQueryDataCall err=0, call_state=2
[03-20_22:41:59:956] ifconfig usb0 up
[03-20_22:41:59:969] busybox udhcpc -f -n -q -t 5 -i usb0
udhcpc: started, v1.30.1
udhcpc: sending discover
udhcpc: sending select for 10.33.63.96
udhcpc: lease of 10.33.63.96 obtained, lease time 86400
[03-20_22:42:00:159] AT> AT+QNETDEVCTL?
[03-20_22:42:00:162] AT< +QNETDEVCTL: 1,1,1,1
[03-20_22:42:00:162] AT< OK
[03-20_22:42:00:162] AT> AT+CGACT?
[03-20_22:42:00:166] AT< +CGACT: 1,1
[03-20_22:42:00:166] AT< OK
[03-20_22:42:00:166] requestQueryDataCall err=0, call_state=2
[03-20_22:42:15:182] AT> AT+QNETDEVCTL?
[03-20_22:42:30:183] requestQueryDataCall err=-4, call_state=1
[03-20_22:42:30:184] ifconfig usb0 0.0.0.0
[03-20_22:42:30:197] ifconfig usb0 down
[03-20_22:42:30:212] AT> AT+CGACT?
[03-20_22:42:45:214] requestSetupDataCall err=-4
[03-20_22:42:45:214] try to requestSetupDataCall 5 second later
[03-20_22:42:50:215] AT> AT+CGACT?
[03-20_22:43:05:216] requestSetupDataCall err=-4
[03-20_22:43:05:217] try to requestSetupDataCall 10 second later
[03-20_22:43:15:218] AT> AT+CGACT?
[03-20_22:43:30:219] requestSetupDataCall err=-4
[03-20_22:43:30:219] try to requestSetupDataCall 20 second later
[03-20_22:43:50:235] AT> AT+CGACT?
[03-20_22:44:05:237] requestSetupDataCall err=-4
[03-20_22:44:05:238] try to requestSetupDataCall 40 second later
[03-20_22:44:45:269] AT> AT+CGACT?
[03-20_22:45:00:271] requestSetupDataCall err=-4
[03-20_22:45:00:272] try to requestSetupDataCall 60 second later
requestSetupDataCall[03-20_22:46:00:319] AT> AT+CGACT?
[03-20_22:46:15:321] requestSetupDataCall err=-4
[03-20_22:46:15:321] try to requestSetupDataCall 60 second later
[03-20_22:47:15:368] AT> AT+CGACT?
[03-20_22:47:30:370] requestSetupDataCall err=-4
[03-20_22:47:30:370] try to requestSetupDataCall 60 second later
帮我看看是什么原因导致断网的？