FP4 reboots continually in Poland with dual sim enabled

[el_foz]

I’ve had my FP4 for 2 months with no problems. I live in Spain and have a brand new physical Orange sim and a brand new Vodafone esim.
On Friday I arrived in Poland for the weekend and after turning off airplane mode the phone started to reboot constantly. The only to avoid it was to not enter the pin for one of the sims. I’ve done various experiments over the weekend and the conclusion is that as soon as I enable two sims it starts to crash and reboot. Either sim enabled by itself is fine.
Haven’t applied any updates recently, including android 12.
On the way back to Spain now so won’t be able to test much for a while. Hoping the same doesn’t happen in the UK next month! It was fine in Sweden, Switzerland and Germany last week.

[el_foz]

Turned both sims on 20 minutes ago at the airport and rebooted on purpose. No problems so far. Maddening!

…

But now it rebooted, when writing a WhatsApp message on the bus to the plane. Probably due to changing mobile network cell because I finally moved. It was fine while stationary in the airport bar. After disabling the physical sim again it’s stable again.

Conclusion - negotiating connection to a cell is the issue. But only when both sims are enabled and I’m in Poland (Warsaw).

[Jorge]

Same thing happened to me last year on several occasions when visiting Warsaw, when trying to enable the eSIM from KPN NL. This was one of the deciding factors for returning the phone.

[B_Jay]

I have the same problem in Germany with Telekom(private physical) and Vodafone(company eSIM).
I found a half solution.
First, the telekom support told me, that they and vodafone use different WLAN Call systems, and that this can cause trouble.
Also i spoke to the FP support, they offered some steps to test.
(My main point are the wifi Calls, but i tested it with turning on/off airplanemode+wifi)

So one workaround was: turning off 5G on the Telekom card.
OR: turning off Vodafone Mobile Data at all and wifi call.
After using telekom wifi call i was also able to enable Vodafone mobile Data again, without crashes, which seems like telekom needs to download their wifi call stuff without Vodafone in the way. (i kept vodafone wifi calls disabled.)

Funfact: as long the Vodafone eSIM is activated, Telekom won’t use Wifi Calls unless its in airplane mode, doesn’t matter how the mobile data settings are.
(While Vodafone always uses wifi calls if enabled etc.)

So nothing perfect here, i hope they fix at least, that telekom uses the wifi calls when vodafone is enabled, because i don’t rly. need wifi calls on my company number.
But everything is stable atm, as long wifi calls on Vodafone are deactivated.

And for your case, try to disable wifi calls and mobile data on both cards, reboot, try airplane mode+ wifi on and off, if that works, turn on mobile data on one, than on both, etc.
And if you want to use wifi calls, you may could only use it on one card and you should acitvate and make a fist use while the other card is fully deactivated.
And also dont forget to reboot after those changes, worked better for me.