No connection to mobile network possible

Using /e/OS Troubleshooting
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1

Hello all,

I am experiencing issues with connections to the mobile network on my FP4, since a few days before the update to /e/OS 4.0.

  • Two SIMs (a physical one and an eSIM) from two different carriers from two different countries are affected.
  • Both SIM cards are detected
  • The APN settings are according to the carrier.
  • The physical SIM works in an older phone.
  • Turning “Aeroplane mode” on and then off will resolve the issue for a short time.
  • Resetting mobile network settings (System > Reset options) did not help

Is there anyone around that could help me to figure out what causes the issues and if it is a hardware or software issue?

I would like to avoid resetting to factory settings as that would cause a lot of work…

Pixel 9 Pro (caiman): no mobile connection on e-sim after update to 4.0
FP4: Intermittent missing incoming SMS on physical SIM when eSIM is enabled
2

Please try

Settings > :magnifying_glass_tilted_left: Search: Access Point names > top right 3 dot menu > Restore defaults.

Straight after, switch to airplane mode 10 seconds and return.

If not works try again APN > Restore defaults and power down. Test again after reboot.

3

Hello.
Thank you for your reply.

I tried both without success. I also noticed that the APN gets reset to something that according to the carrier is wrong. (Authentication method is set to none instead of CHAP and MVNO is set to IMSI instead of None)

Therefore I tried (for my physical SIM):

  1. Resetting, Aeroplane mode on (10+s) and off
  2. Resetting, Correcting APN, Aeroplane mode on (10+s) and off
  3. Resetting, restart
  4. Resetting, correcting APN, restart
  5. Trying a different SIM (unfortunately from the same carrier)

Afterwards I can (sometimes) load half a webpage before it stops working…

4

For the physical SIM I suggest first to check for successful IMS registration like this Wifi calling not working, e OS 3.5 on FP6 - #3 by tcecyk

If this shows correct then I would phone the carrier and ask for a Network reset. This may or may not be the same as APN reset.

MVNO is set to IMSI instead of None

I don’t know the full significance of this but it seems MVNO are a little more prone to difficulties with ~early 2026 changes to the APN “system” in AOSP. Loosely speaking IMSI would seem an improvement on None.

If you phoned the carrier you might ask if that is a recent change.

5

You might have to be more specific about this. Carriers are defined by country (within AOSP APN “system”), so are you effectively roaming on one service?

6

Thank you for your suggestions.

I just checked the IMS registration: Not registered
Everything else (Voice over…, etc.) is unavailable.
Interestingly, even when the status bar on top shows that the connection is working (no exclamation mark), the IMS registration is not registered.

I got the data by entering the *# code mentioned in the linked topic, and opened the “IMS service status” in the “three dot menu”.

What I forgot to mention is, that also SMS won’t work during the disconnects (calls probably too, but it is not tested). Which is not surprising, I think.

Yes, I am roaming with my secondary SIM (eSIM).

In case it might help:

  1. SIM1: Vimla (Sweden), using Telenor net, physical SIM, not roaming
  2. SIM2: HoT (Austria), using T-Mobile net (might also use others according to various websites), eSIM, roaming, usually data is not used
7

So is this the physical SIM? Either way just ask the carrier first (just as above except IMS is missing too) … in speaking to the carrier you might also just ask “might I need a new SIM?” It is always possible that an older SIM cannot manage new “methods” SIM recognizes, but no network - #9 by badslipper.

Worst case there is the possibility that some carriers with some devices might depend on this from the install page.

Additionally, some devices require that VoLTE/VoWiFi be utilized once on stock to provision IMS.

With two carriers you will need to check for two ISM registrations (by juggling with which SIM you dial INFO).

In troubleshooting I believe we need to consider that APN data needs to harmonise, well match,

  • on your SIM card,
  • provided on /e/OS install and
  • your carrier’s latest APN

The IMS registration (may not be essential for “minimal service” ??) Helps to pull all three together, even to the extent of writing “improved data” to the SIM card.

8

Hopefully, what we said so far all applies to the pysical SIM and while it might be behaving as Primary SIM … if that SIM is incompetent without IMS … then e-SIM problems might be hard to define ??

As I understand the secondary SIM will avoid mobile data, leaving that to primary.

Roaming might not include mobile data, see T&C (or require a switch in settings).

9

Yes, it is the physical SIM, which is the primary SIM.
However, the eSIM encounters the same issues and does not connect properly either.

Done, let’s see how long it will take for an answer and if they will do that.
I also asked them to confirm the correct APN settings.

How do I get the APN settings for the SIM and the /e/OS install?
If I reset the APN settings, wouldn’t that be the ones on the SIM or from /e/OS?

I usually try each step for both SIM cards, separately.
However, I usually have the mobile data for the eSIM completely turned off in the settings. I also turned off the option to use the second SIM to improve connectivity.

I just realized that I can turn off the eSIM, which I did right now to avoid any influence of the eSIM on the issue.

10

This is getting very weird.
After turning off the eSIM I realized that the connection works flawless (tested for a while)
As soon as I turn on the eSIM the issue reappears.

I the tried deactivating the physical SIM and using only the eSIM. Mobile data works fine.

So it seems that having two active SIMs will cause connection issues for both. If only one active SIM is present, everything works.

I think I will see if I can erase and redownload the eSIM to see if that helps…

Btw. IMS is not registered in the working state either…

11

Is part of what I meant by

We seem to be working along the same lines … get physical fully working first …

There I refer to the things that have already been thrown at the device.

If necessary we can explore the “presets” which come with the /e/OS install if you find any evidence that your carrier’s published settings for your plan / SIM are wrong, like this Wrong APN settings Telia Norway.

  1. When you (earlier, Post #2, 3)
    Reset Default + Airplne and
    Reset Default + restart you hope to connect to your carrier, and the carrier automatically reponds by trying to write the correct data wherever needed to do the mentioned “harmonisation”.
  2. You would get your carrier’s published APN and create (add) a new APN set at

Settings > :magnifying_glass_tilted_left: Search: Access Point Names.

So loosely speaking IMS is a one off event where the carrier registers the device “permanently” into their network specifically for

The system carriers use to deliver modern voice and messaging over 4G/5G. If “IMS registration” is shown as “Registered”, your device can use VoLTE, SMS over IMS and Wi‑Fi Calling (subject to your carrier plan and device support).

So we used to be able to live without it … increasingly it is required for advanced methods which carriers may use under the hood and maybe especially in virtual networks (you mentioned MVNO Mobile virtual network operator).

Understood, but “Divide and rule”. I kept my e-SIM comments on a separate post just so we understand what we are trying to do. Two problems will be interdependent, acknowledged) but my training says never attempt to solve two problems at the same time or you will never know what fixed what.

12 
Duplicating much of what we are doing.

APN Setting and Troubleshooting 2026

What’s changed

Since ~early 2026 users are no longer required to enter values for MCC and MNC as part of APN settings. APN settings will be published by your carrier; be sure to get up to date data.

One would hope that the APN data will match

  • on your SIM card,
  • provided on /e/OS install and
  • your carrier’s latest APN.

APN will likely fail if the SIM card data cannot be updated to exact current values.

In case of difficulties one can ask the carrier to do an APN reset OTA (Over The Air) … alternatively

Manual APN Configuration

Ensure you have a good Wi-Fi connection.

Open Settings :mag: Search APN … or

Navigate to Mobile Networks:

Tap on Wireless & networks or Connections.

Select Mobile networks or Mobile data.

Access APN Settings:

Tap on Access Point Names or APN.

Add New APN:

Tap on the ‘+’ icon or Add button to create a new APN.

Enter APN Details:

Fill in the required fields based on your carrier’s specifications.

Save APN Settings:

Tap on Save or the checkmark icon to save the new APN.

It is OK if Save takes a while complete … implies the the settings have been checked valid by the carrier.

Troubleshooting

If you encounter issues while setting APN, consider the following steps:

Reset to Default: Navigate to APN settings, tap on top right 3 dot menu, and select Reset to default.

Activate Airplane Mode: Enable Airplane mode, wait for a few seconds, and then disable it to refresh the network settings.

Restart Device: Restart your phone while connected to Wi-Fi to refresh the network settings.

Perhaps be prepared to sequence the above differently.

Carrier-Specific APN Settings

For specific APN settings, refer to your carrier’s documentation.

Nothing - CMF Phone 1 - tetris - Documentation Suggestions
13

I will definitely ask both providers to do a network reset and get their correct APN settings.

However, I start to think that it is a software problem.
The same APN settings work as long only a single SIM is active. It doesn’t matter which is active.
(To activate/deactivate I go to “Network and Internet” > “SIMs” > “Vimla”/" HoT" and flip “Use this SIM”, see screenshot at the bottom)

So:

  • Only physical SIM active: connection works
  • Only eSIM active: connection works
  • Both SIMs active: no connection (both SIMs)

Therefore, it seems like trying to connect to two separate mobile networks, causes no connection at all.

Screenshot_20260701-164613_Settings
Screenshot_20260701-164613_Settings1080×2340 44.7 KB

14

Alright, I did some more testing.

IMS registration error seems a separate issue:
Turning on 4G calling and deactivating WiFi calling solved the IMS registration in all situations. So sms and calls work.

Having only one active SIM (either HoT or Vimla) works flawless (sms, calls, mobile data). Therefore, I guess it is safe to assume that APN settings or carrier settings are not the issue.

Two active SIM

  • vimla: no mobile data, sms sending and delivery very slow, calls seem to work
  • HoT: no mobile data, sms work (without issues), calls are untested

By now, I am quite sure that it is an issue with /e/OS and therefore, I’ll create a bug report soon

15

Bug reports have been created:

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16

Good work.

In case there is some not fully understood connection please could I suggest that you make a link on your Gitlab work items from

to both of your APN issues

and

17

It’s done.
Fingers crossed that it will be solved soon

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