Mobile data connection breaks after few minutes using dual SIM

There is a problem with Telekom at the moment. Fairphone is working on it, as explained in the following message.

The topic here is about the FP4 however you linked FP5 information (only applicable for Germany )
So not sure this is connected.

@jamesmcstrid a few more details would be helpful

Can you please share your exact OS version?

FP4.TP20.C.087.20231122
Android 13

Incredible. I switched of my eSIM and WiFi and using my Telekom SIM, I am now online for already more than 30 minutes. So I guess this is a workaround and may help to trace down the problem further. While I can not receive calls on my other number, this is already helping a lot as when I am lost in the wild, I can get Internet this way. Thank you for this hint.
Also this implies to me that my hardware is not broken what is good news for me.

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Your OS version is up-to-date. That’s good.
And great that you’ve found an “emergency workaround” for now. Maybe you’ll even need some more testing to get closer to the root of the problem…
I suppose it’s time to contactsupport.

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I have the exact same issue on my fp4. My provider is tele2. Did anyone manage to solve this?

I am on lineageOS but have the same problem. I have two german sim cards: physical one from congstar (breaks), esim from Vodafone (works fine). Workaround for me is to go into the congstar Sim settings, change “Preferred network type” to 3G and back to 5G. After that, mobile data works again.

So far no solution but seems all very similar. My phone will be officially sent to the repair centre these days and let’s hope they can fix it.

I happen to be a computer scientist who is hunting for bugs every day. So with all the details posted here and in related threads let me draw an updated conclusion:

  • I had permanent mobile data connection when my FP4 was new for 1 year or so and I have dual SIM + SD-Card inserted and active from day 1
  • After some time and some updates this error occurred
  • Several workarounds have been reported how to still get mobile data connection so we can exclude that APNs and ISPs are not operational causing the connectivity problem AND that it is a general hardware damage issue (eSIM is working and can take phones and phone can have mobile data connection but both at the same time may not be working or only with strange 3G/5G workaround that I could not yet verify)
  • It does not seem that all FP4 Dual-SIM users are affected. Maybe it only happens in additional combinations (German frequency bands / Combination of SIM and eSIM Providers / …). At least enough users have confirmed they are affected and there is some problem with FP4 and Dual-SIM.
  • Since a user reported, he has the issue with LineageOS it is not a software issue on a higher level.
  • However, I assume that some low-level driver or firmware update has caused this problem in H2/2023. Are there other FP4 Dual-SIM users that install updates recently can confirm or deny that the problem occurred within this time-frame?

After all we hope the root cause of this issue can be traced down and fixed soon.
Thank you very much

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My set-up is:

Physical SIM in the German Vodafone Network and eSIM within the German O2 Network. No 5G per contract and mobile data on the eSIM disabled as I dont have a data plan for this SIM.

I dont use the FP4 as my main phone and would say I dont have the issue, however will try to take it with me in the train next week and use it for some time during travel.

You can call *#*#0574#*#*

Update: I used the FP4 the past days a few times while travelling in train and had no issues at all. So wondering if this is somehow provider specific, and see a lot German Telekom I think.

I just got feedback about my repair: exchange of the motherboard and an update, no more details provided. Will check whether that fixed the issue once my phone is back with me.