Modem never connects to LTE

RE: Modem never connects to LTE

Baowz — Tue, 30 Nov 2021 10:15:01 GMT

I found a working solution!
By doing a factory reset on the modem it started connecting with LTE again. I sadly do not have a reason why it was a problem in the first place. But by doing this command:

AT%XFACTORYRESET=0

Everything started working as normal. Hope this helps others as well. 🙂

RE: Modem never connects to LTE

Håkon Alseth — Fri, 05 Nov 2021 14:14:56 GMT

Do you use the same sdk version on both PCs?

You need to check the details of the log from the network in both cases, to see if there's any differences in the network provider you're connected to as well as the specific cell tower.

RE: Modem never connects to LTE

Baowz — Fri, 05 Nov 2021 13:30:41 GMT

It's the same result for Telenor. I just tried it with a "soracom" IoT card that came with the board and it has the same result as all the other sim cards. As I mentioned earlier some of the boards started working again just by flashing the code again from a different computer. Even though it is the same code, is it possible that some of the settings on the computer I'm using are different or anything similar?

RE: Modem never connects to LTE

Håkon Alseth — Fri, 05 Nov 2021 09:55:47 GMT

Hi,

Note that you're selecting Telia now, and not Telenor.

I would recommend that you get a dedicated "iot" SIM card from your vendor to use with the nRF9160. It is clear that the one you're using at this time will roam to networks that does not allow LTE M1 / NB1 connectivity.

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Thu, 04 Nov 2021 15:03:26 GMT

[quote userid="2115" url="~/f/nordic-q-a/81188/modem-never-connects-to-lte/337473#337473"]Did you ensure that AT+CFUN was 0 or 4 before selecting the network manually?[/quote]

That explains the timeout, I did not ensure this. After doing so this is what happened:

AT+CFUN=0
+CEREG: 0
OK
AT+COPS=1,2,"24202"
OK

I got a signal strength that differentiated between 2 and 3 bars until it settled at 2 bars.

However, it is still not connecting with an IP address. I still find it weird that some of the boards worked when I flashed the code from a different computer and others still don't work even though I did exactly the same with them.

I do want to add that when running the AT+CESQ command now I receive this now:
+CESQ: 99,99,255,255,34,68

RE: Modem never connects to LTE

Håkon Alseth — Thu, 04 Nov 2021 12:53:54 GMT

Hi,

Did you ensure that AT+CFUN was 0 or 4 before selecting the network manually?

Did the network connection stabilize after manually selecting the network?

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Wed, 03 Nov 2021 20:16:17 GMT

For some reason, flashing the code from a different computer made some of the boards work again. No clue why since the code is exactly the same.

RE: Modem never connects to LTE

Baowz — Tue, 02 Nov 2021 16:31:28 GMT

I'm not totally sure if I'm managing to use the AT%CESQ command correctly, apologies for my incompetence. But I've used it the way I think is correct. I also tried to manually connect to the networks that the LTE link monitor is showing that are available (Telenor Norge AS and Telia Norge AS). This is the result of the test:

2021-11-02T16:17:17.568Z DEBUG modem << LTE Link Connecting ...
2021-11-02T16:17:19.555Z DEBUG modem >> AT%CESQ=1
2021-11-02T16:17:19.570Z DEBUG modem << OK
2021-11-02T16:17:38.563Z DEBUG modem >> AT%CESQ
2021-11-02T16:17:38.576Z DEBUG modem << OK
2021-11-02T16:17:45.842Z DEBUG modem << +CEREG: 2,"0901","02152420",7,0,0,"11100000","11100000"
2021-11-02T16:17:45.890Z DEBUG modem << +CSCON: 1
2021-11-02T16:17:46.117Z DEBUG modem << +CEREG: 4,"0901","02152420",7,0,15,"11100000","11100000"
2021-11-02T16:17:47.367Z DEBUG modem << +CSCON: 0
2021-11-02T16:17:47.401Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-11-02T16:17:48.610Z DEBUG modem << +CEREG: 2,"76C1","030E6701",7,0,15,"11100000","11100000"
2021-11-02T16:17:48.658Z DEBUG modem << +CSCON: 1
2021-11-02T16:17:49.026Z DEBUG modem << +CEREG: 0,"76C1","030E6701",7,0,8,"11100000","11100000"
2021-11-02T16:17:50.275Z DEBUG modem << +CSCON: 0
2021-11-02T16:17:52.174Z DEBUG modem >> AT+CESQ
2021-11-02T16:17:52.197Z DEBUG modem << +CESQ: 99,99,255,255,255,255
2021-11-02T16:17:52.205Z DEBUG modem << OK
2021-11-02T16:17:57.852Z DEBUG modem >> AT+COPS=?
2021-11-02T16:18:51.870Z DEBUG modem << +COPS: (1,"","","24202",7),(1,"","","24201",7)
2021-11-02T16:18:51.884Z DEBUG modem << OK
2021-11-02T16:18:51.918Z DEBUG modem >> AT+COPS?
2021-11-02T16:18:51.948Z DEBUG modem << +COPS: 0
2021-11-02T16:18:51.952Z DEBUG modem << OK
2021-11-02T16:19:52.422Z DEBUG modem >> AT+COPS?
2021-11-02T16:19:52.436Z DEBUG modem << +COPS: 0
2021-11-02T16:19:52.443Z DEBUG modem << OK
2021-11-02T16:20:27.896Z DEBUG modem >> AT+CFUN=1
2021-11-02T16:20:27.914Z DEBUG modem << OK
2021-11-02T16:20:29.265Z DEBUG modem >> AT+COPS=1,2,"24201"
2021-11-02T16:20:30.266Z ERROR Error: 'AT+COPS=1,2,"24201"
' timed out
2021-11-02T16:20:37.018Z DEBUG modem << +CEREG: 0,"76C1","030E6D06",7,0,8,"11100000","11100000"
2021-11-02T16:20:37.045Z DEBUG modem << OK
2021-11-02T16:20:42.114Z DEBUG modem >> AT+CFUN=1
2021-11-02T16:20:42.143Z DEBUG modem << OK
2021-11-02T16:20:43.483Z DEBUG modem >> AT+COPS=1,2,"24202"
2021-11-02T16:20:44.483Z ERROR Error: 'AT+COPS=1,2,"24202"
' timed out
2021-11-02T16:20:52.076Z DEBUG modem << +CEREG: 0,"0901","02152420",7,0,8,"11100000","11100000"
2021-11-02T16:20:52.083Z DEBUG modem << OK
2021-11-02T16:21:54.092Z DEBUG modem >> AT+CFUN=1
2021-11-02T16:21:54.139Z DEBUG modem << OK
2021-11-02T16:21:55.637Z DEBUG modem >> AT+CESQ
2021-11-02T16:21:55.674Z DEBUG modem << +CESQ: 99,99,255,255,255,255
2021-11-02T16:21:55.706Z DEBUG modem << OK

RE: Modem never connects to LTE

Håkon Alseth — Tue, 02 Nov 2021 15:56:52 GMT

Hi,

Looks like you called the AT command when you're not connected, or you have been in PSM (ie. sleep) for a longer period.

Try issuing AT%CESQ=1 (see here for more documentation) to enable notifications to the application when there's a change in the signal strength.

[quote user="Baowz"]Does this have anything to do only with the sim card or the board as well? Because the sim card works on prototypes that do not have this issue (The nRF9160 Feather boards). However, any sim card on any of the Icarus boards does not manage to connect again after they got disconnected on the very first boot up.[/quote]

I understand, but this is not a guarantee when using a "non IoT" SIM card.

What you can do is, when you're connected to the "good network", issue "AT+COPS?" to see which one this is.

Then see what you get back and manually specify this network as your preferred network, as described in the documentation:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cops_set.html?cp=2_1_7_0_0

"24201" would be telenor norway for instance:

https://en.wikipedia.org/wiki/Mobile_network_codes_in_ITU_region_2xx_(Europe)#Norway_%E2%80%93_NO

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Tue, 02 Nov 2021 15:38:23 GMT

Does this have anything to do only with the sim card or the board as well? Because the sim card works on prototypes that do not have this issue (The nRF9160 Feather boards). However, any sim card on any of the Icarus boards does not manage to connect again after they got disconnected on the very first boot up.

This is the information it gives me sending the messages you provided:

AT%CESQ
ERROR
AT+CESQ
+CESQ: 99,99,255,255,255,255

I truly appreciate your help and effort in solving this issue with me. I have learned a lot.

RE: Modem never connects to LTE

Håkon Alseth — Tue, 02 Nov 2021 13:58:35 GMT

In SIM cards, you have PLMN, which is essentially a list of network identifiers.

Within this list, you have "home PLMN" and "visitor PLMN", the latter is used for preferred networks in roaming scenarios.

It might be that the list in the sim card includes towers that don't provide you with LTE M or NB1 connectivity. This could be because the initial tower you're connected to has too low signal strength, but it would be guesswork from my side, as you'd need to verify this by subscribing to AT%CESQ or AT+CESQ to view the signal strength (RSRP).

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Mon, 01 Nov 2021 18:39:28 GMT

This is a "normal" sim card. However, the cards that are being used are currently working on nRF9160 Feather boards and have been working on Icarus IoT boards as well until recently. I haven't specifically checked if it does support NB1 and LTE-M, but given that it works on some boards and has been working previously I'm pretty certain. The cards are working as normal when connected to my phone if this gives any valuable information.

RE: Modem never connects to LTE

Håkon Alseth — Mon, 01 Nov 2021 17:59:06 GMT

Hi,

It seems to try several towers, which all throw you out, and after 10 minutes it tries on NB1 instead of LTE-M, and repeats the same process.

You can see this when '7' turns to a '9' in CEREG.

The cell id that seems to accept your connection is "020A6016", where you are registered as roaming. Is this a "IoT" sim card or a "normal" one? Have you checked if they have roaming for NB1 and LTE-M?

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Mon, 01 Nov 2021 17:46:53 GMT

I also get "14" at certain times. From what I've gathered this means "EPS services not allowed in this PLMN". Is it possible that the device somehow has gotten "banned" from using the LTE network?

2021-11-01T16:38:30.217Z DEBUG modem << LTE Link Connecting ...
2021-11-01T16:38:56.652Z DEBUG modem << +CEREG: 2,"0901","02022520",7,0,0,"11100000","11100000"
2021-11-01T16:38:56.700Z DEBUG modem << +CSCON: 1
2021-11-01T16:38:56.908Z DEBUG modem << +CEREG: 4,"0901","02022520",7,0,15,"11100000","11100000"
2021-11-01T16:38:58.156Z DEBUG modem << +CSCON: 0
2021-11-01T16:38:58.189Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-11-01T16:38:58.460Z DEBUG modem << +CEREG: 2,"76C1","030D6B01",7,0,15,"11100000","11100000"
2021-11-01T16:38:58.508Z DEBUG modem << +CSCON: 1
2021-11-01T16:38:58.844Z DEBUG modem << +CEREG: 0,"76C1","030D6B01",7,0,8,"11100000","11100000"
2021-11-01T16:39:00.092Z DEBUG modem << +CSCON: 0
2021-11-01T16:49:42.401Z DEBUG modem << +CEREG: 2,"0CE9","01E35013",9,0,8,"11100000","11100000"
2021-11-01T16:49:42.546Z DEBUG modem << +CSCON: 1
2021-11-01T16:49:42.721Z DEBUG modem << +CEREG: 2,"0CE9","01E35013",9,0,14,"11100000","11100000"
2021-11-01T16:49:52.721Z DEBUG modem << +CSCON: 0
2021-11-01T16:49:57.906Z DEBUG modem << +CEREG: 2,"9DD1","030D6B65",9,0,14,"11100000","11100000"
2021-11-01T16:58:30.284Z DEBUG modem << LTE Link Connected!
2021-11-01T16:58:30.310Z DEBUG modem << ERROR: getaddrinfo failed -11
2021-11-01T16:58:30.312Z DEBUG modem << Failed to initialize broker connection
2021-11-01T16:58:30.314Z DEBUG modem << ERROR: client_init -10

RE: Modem never connects to LTE

Baowz — Fri, 29 Oct 2021 11:53:19 GMT

The sim card I'm using is bought through gudbrandsdalen energi/mobil, currently, I've used 0.12/99GB this month. So it is not the data on the sim card. I have also tried switching the sim card with my own (both cards have pin disabled). For some reason though, my very first prototype is still working and running as it should, and that one uses a "twin" sim card. I even switched back and forth the cards to make sure that the sim was not the problem.

RE: Modem never connects to LTE

Håkon Alseth — Fri, 29 Oct 2021 11:34:06 GMT

Hi,

Are you by any chance using a iBasis SIM card? Note that this has a limit of 10 MByte.

It seems that you have problems registering after a reset:

2021-10-28T03:52:03.826Z DEBUG modem << +CEREG: 2,"0901","01E3500B",7,0,0,"11100000","11100000"
2021-10-28T03:52:03.874Z DEBUG modem << +CSCON: 1
2021-10-28T03:52:04.082Z DEBUG modem << +CEREG: 4,"0901","01E3500B",7,0,15,"11100000","11100000"
2021-10-28T03:52:05.330Z DEBUG modem << +CSCON: 0
2021-10-28T03:52:05.362Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-10-28T03:52:06.130Z DEBUG modem << +CEREG: 2,"76C1","030D6B01",7,0,15,"11100000","11100000"
2021-10-28T03:52:06.162Z DEBUG modem << +CSCON: 1
2021-10-28T03:52:06.482Z DEBUG modem << +CEREG: 0,"76C1","030D6B01",7,0,8,"11100000","11100000"
2021-10-28T03:52:07.730Z DEBUG modem << +CSCON: 0

The "15" and the "8" just before the bitmask is indicating that there's an error returned by the network (EMM/ESM cause codes).

8 = EPS services and non-EPS services not allowed

15 = No suitable cells in tracking area

Could be that you're out of data on your sim card.

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Fri, 29 Oct 2021 11:27:51 GMT

I'm not able to use a newer version because that messes with the UART connection with the camera for some unknown reason (https://forums.adafruit.com/viewtopic.php?f=19&t=183229). But does the version matter though, given that it's been working perfectly fine before, the only difference is that it's a new camera but the same model and version, could it somehow interfere with the modem?

RE: Modem never connects to LTE

Håkon Alseth — Fri, 29 Oct 2021 10:40:35 GMT

Hi,

It seems that you're running an older version of ncs, based on the zephyr boot banner print.

Could you try updating to a newer version? There's been plenty of bug fixes in ncs since v1.3.0.

Kind regards,

Håkon

RE: Modem never connects to LTE

Baowz — Thu, 28 Oct 2021 11:35:10 GMT

After letting the board search for a while I managed to get this message:

2021-10-28T11:08:40.232Z DEBUG modem << *** Booting Zephyr OS build v2.3.0-rc1-ncs3  ***
2021-10-28T11:08:40.233Z DEBUG modem << Camera VC0706
2021-10-28T11:08:40.235Z DEBUG modem << Initializing camera
2021-10-28T11:08:43.239Z DEBUG modem << 640x480
2021-10-28T11:08:43.255Z DEBUG modem << Setting up compression ratio
2021-10-28T11:08:43.271Z DEBUG modem << Current compression ratio is 55
2021-10-28T11:08:43.273Z DEBUG modem << Provisioning certificates
2021-10-28T11:08:44.759Z DEBUG modem << LTE Link Connecting ...
2021-10-28T11:08:53.671Z DEBUG modem << +CEREG: 2,"76C1","030D6B01",7
2021-10-28T11:18:44.822Z DEBUG modem << +CEREG: 0
2021-10-28T11:19:44.179Z DEBUG modem << +CEREG: 2,"9DD1","030D6B65",9
2021-10-28T11:20:36.272Z DEBUG modem << +CSCON: 1
2021-10-28T11:20:36.802Z DEBUG modem << +CEREG: 0
2021-10-28T11:20:46.816Z DEBUG modem << +CSCON: 0
2021-10-28T11:28:44.836Z DEBUG modem << LTE Link Connected!
2021-10-28T11:28:44.862Z DEBUG modem << ERROR: getaddrinfo failed -11
2021-10-28T11:28:44.863Z DEBUG modem << Failed to initialize broker connection
2021-10-28T11:28:44.863Z DEBUG modem << ERROR: client_init -10

The time from boot till the connection is very close to exactly 20 min. Is there maybe some kind of setting that needs to be changed?