# Sierra EM7455 LTE drop connection after a while **URL:** \ **Category:** MC/EM Series\ **Created:** [January 28, 2020, 1:54pm UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152 "2020-01-28T13:54:18Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![amitmulayoff](https://avatars.discourse-cdn.com/v4/letter/a/9fc29f/32.png) [@amitmulayoff](https://forum.sierrawireless.com/u/amitmulayoff)\ **Post date:** [January 28, 2020, 1:54pm UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/1 "2020-01-28T13:54:18Z")
Hello guys i have an issue when using Sierra EM7455 LTE on Ubuntu 18.04 kernel 4.15.0-72 **raw ip mode** im trying to establish connection and im using qmicli (1.22.0 version) commnads: 1: “qmicli -d /dev/cdc-wdm0 --set-expected-data-format=raw-ip” 2: “qmicli -d /dev/cdc-wdm0 --wds-start-network=“apn=internetg,ip-type=4” --client-no-release-cid” then i can see in “qmicli -d /dev/cdc-wdm0 --wds-get-current-settings” for exmple [/dev/cdc-wdm0] Current settings retrieved: IP Family: IPv4 IPv4 address: 10.210.105.53 IPv4 subnet mask: 255.255.255.252 IPv4 gateway address: 10.210.105.54 IPv4 primary DNS: 194.90.0.11 IPv4 secondary DNS: 212.143.0.11 MTU: 1500 Domains: none i can alos see in AT!SCACT? that it is : !SCACT: 1,1 but after copule of hours i see that !SCACT: 1,0 and the output of “qmicli -d /dev/cdc-wdm0 --wds-get-current-settings” is error: couldn’t get current settings: QMI protocol error (15): ‘OutOfCall’ i see in atthat : +CGCONTRDP: 1,5,internetg,10.133.205.175,194.90.0.11,212.143.0.11 ``` AT!SCACT? !SCACT: 1,0 ``` meanig that the ip has change (im not using static ip APN service ) but its not reflacting to the qmicli commands pls if someone can advice , thanks in advance!! here is more dump of maybe relevet AT commands : ATI Manufacturer: Sierra Wireless, Incorporated Model: EM7455 Revision: SWI9X30C\_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09 MEID: 35907306077906 IMEI: 359073060779067 IMEI SV: 12 FSN: LF815621960110 +GCAP: +CGSM OK **AT!PCINFO?** State: Online LPM voters - Temp:0, Volt:0, User:0, W\_DISABLE:0, IMSWITCH:0, BIOS:0, LWM2M:0, OMADM:0, FOTA:0 LPM persistence - None OK Temperature: 45 Reset Counter: 1 Mode: ONLINE System mode: LTE PS state: Attached LTE band: B3 LTE bw: 20 MHz LTE Rx chan: 1400 LTE Tx chan: 19400 LTE CA state: NOT ASSIGNED EMM state: Registered Normal Service RRC state: RRC Idle IMS reg state: No Srv PCC RxM RSSI: -57 RSRP (dBm): -91 PCC RxD RSSI: -62 RSRP (dBm): -95 Tx Power: 0 TAC: 03A4 (932) RSRQ (dB): -13.8 Cell ID: 0038431F (3687199) SINR (dB): 2.2 OK **AT!PCTEMP?** Temp state: Normal Temperature: 45.00 C OK **AT!PCVOLT?** Volt state: Normal Power supply voltage: 3296 mV (ADC: 35850) OK **AT+CPIN?** +CPIN: READY OK **AT!IMPREF?** !IMPREF: preferred fw version: 02.24.05.06 preferred carrier name: GENERIC preferred config name: GENERIC\_002.026\_000 current fw version: 02.24.05.06 current carrier name: GENERIC current config name: GENERIC\_002.026\_000 OK **AT+COPS?** +COPS: 0,0,“Cellcom IL Cellcom”,7 OK **AT+CGDCONT?** +CGDCONT: 1,“IP”,“internetg”,“0.0.0.0”,0,0,0,0 OK ---
**Author:** ![amitmulayoff](https://avatars.discourse-cdn.com/v4/letter/a/9fc29f/32.png) [@amitmulayoff](https://forum.sierrawireless.com/u/amitmulayoff)\ **Post date:** [January 29, 2020, 12:39pm UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/2 "2020-01-29T12:39:01Z")
someone can help maybe? ---
**Author:** ![Oedenburger](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/oedenburger/32/4028_2.png) [@Oedenburger](https://forum.sierrawireless.com/u/Oedenburger)\ **Post date:** [January 30, 2020, 4:50pm UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/3 "2020-01-30T16:50:48Z")
the NTWK can drop the connection for a number of reasons. The modem will re-attach and acquire a new IP - this is normal. The host should handle such cases and re-establish the session between the host & modem. James ---
**Author:** ![amitmulayoff](https://avatars.discourse-cdn.com/v4/letter/a/9fc29f/32.png) [@amitmulayoff](https://forum.sierrawireless.com/u/amitmulayoff)\ **Post date:** [February 2, 2020, 7:04am UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/4 "2020-02-02T07:04:49Z")
thanks for the replay! how can i identifay those cases? or the host shout handle it automateclly? if not , what should be done to restore connection ? ---
**Author:** ![Sierra\_JordanZhao](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/sierra_jordanzhao/32/4974_2.png) [@Sierra\_JordanZhao](https://forum.sierrawireless.com/u/Sierra_JordanZhao)\ **Post date:** [February 3, 2020, 8:14am UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/5 "2020-02-03T08:14:03Z")
Maybe you can write a IP/DNS lookup program to check the network connectivity periodically. ---
**Author:** ![Oedenburger](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/oedenburger/32/4028_2.png) [@Oedenburger](https://forum.sierrawireless.com/u/Oedenburger)\ **Post date:** [February 5, 2020, 7:06pm UTC](https://forum.sierrawireless.com/t/sierra-em7455-lte-drop-connection-after-a-while/19152/6 "2020-02-05T19:06:45Z")
When you bring up the connection between the modem & host (AT!scact=1 or QMI), the modem is notifies the host via a QMI unsolicited call. GobiNet driver monitors these interface up/down calls and the link up/down msg will be propagated to upper layers. For example you can monitor linkup/down with ethtool: root@nano:/home/sierra# ethtool enp0s20u6i8 Settings for enp0s20u6i8: Current message level: 0x00000007 (7) drv probe link Link detected: no root@nano:/home/sierra# ethtool enp0s20u6i8 Settings for enp0s20u6i8: Current message level: 0x00000007 (7) drv probe link Link detected: yes James