EM7430 unidirectional traffic - packets sent out, no response coming back

IoT Modules MC/EM Series
1

I am having a problem where sometimes the connection is unusable. The connection is established. PPP interface is up and has an IP address, the packets are sent out (can be seen in tcpdump) but no responses are coming back. But from time to time the connection is working fine.
I tried different simcard, from different operator and the problem is present on all mobile networks I tried.

Here’s some info about my modem:

AT!ENTERCND=“A710”
ERROR
ATI3
Manufacturer: Sierra Wireless, Incorporated
Model: EM7430
Revision: SWI9X30C_02.14.03.00 r6134 CARMD-EV-FRMWR2 2016/03/28 14:34:14
MEID: 35907506005263
IMEI: 359075060052635
IMEI SV: 6
FSN: LR605103230410
+GCAP: +CGSM

OK
AT+CPIN?
+CPIN: READY

OK
AT!BAND?
Index, Name
00, All bands

OK
AT+CGDCONT?
+CGDCONT: 1,“IP”,“gprs.swisscom.ch”,“0.0.0.0”,0,0,0,0

OK
AT!SELRAT?
!SELRAT: 06, LTE Only

OK
AT!GSTATUS?
!GSTATUS:
Current Time: 40454 Temperature: 44
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B28 LTE bw: 15 MHz
LTE Rx chan: 9435 LTE Tx chan: 27435
LTE CA state: NOT ASSIGNED
EMM state: Registered Normal Service
RRC state: RRC Idle
IMS reg state: No Srv

PCC RxM RSSI: -83 RSRP (dBm): -114
PCC RxD RSSI: -96 RSRP (dBm): -139
Tx Power: 0 TAC: 1092 (4242)
RSRQ (dB): -12.7 Cell ID: 01141E05 (18095621)
SINR (dB): 0.2

OK
AT+COPS?
+COPS: 0,0,“Swisscom Swisscom”,7

OK
AT+COPS=?
+COPS: (2,“Swisscom”,“Swisscom”,“22801”,7),(1,“Swisscom”,“Swisscom”,“22801”,2),(3,“Salt”,“Salt”,“22803”,7),(3,“Salt”,“Salt”,“22803”,2),(1,“Sunrise”,“Sunrise”,“22802”,2),(1,“Sunrise”,“Sunrise”,“22802”,7),(0,1,2,3,4),(0,1,2)

OK
AT!IMPREF?
!IMPREF:
preferred fw version: 02.14.03.00
preferred carrier name: GENERIC
preferred config name: GENERIC_002.012_000
current fw version: 02.14.03.00
current carrier name: GENERIC
current config name: GENERIC_002.012_000

OK
AT!IMAGE?
TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
FW 1 GOOD 1 0 0 ?? 02.14.03.00?
FW 2 EMPTY 0 0 0
FW 3 EMPTY 0 0 0
FW 4 EMPTY 0 0 0
Max FW images: 4
Active FW image is at slot 1

TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
PRI FF GOOD 0 0 0 000.010_000 02.14.03.00_DOCOMO
PRI FF GOOD 0 0 0 002.012_000 02.14.03.00_GENERIC
PRI FF GOOD 0 0 0 002.013_000 02.14.03.00_TELSTRA
Max PRI images: 50

OK
AT!CUSTOM?
!CUSTOM:
GPSENABLE 0x01
GPSLPM 0x01
IPV6ENABLE 0x01
UIM2ENABLE 0x01
SIMLPM 0x01
USBSERIALENABLE 0x01
SINGLEAPNSWITCH 0x01

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
AT!GETBAND?
!GETBAND: B28

OK

2

can you ping google server?

Does the server receive the packet you sent?

3

No, I can’t ping anything. The server does not receive any traffic I send.

4

You wireshark on module says it is sent out
And the server did not receive, so probably network has problem

5

I thought so too, but I tried different simcard from different operators the problem happens on different mobile networks.
The modem is embedded in a server (Products | Kontron Embedded Computers), so I even tried multiple servers, all have the same problem.

6

No idea, as it does not make sense, you might try different windows pc or ubuntu pc