S21 update to Android 12 - SIM continuously resetting

[gpaolo79]

Hello,

three days ago I have received the update to Android 12 on my Galaxy S21 5G  and, since then, the phone is almost unusable to make phone calls

Both sims reset themselves periodically, within minutes, dropping the network and any phone call in progress. 

After trying to reset the network settings, the phone has started to request the pin for the sims at each reset, so I had to disable it. Keeping one or the other sim active only isn't changing the behaviour. 

The diagnostic on the phone doesn't detect any issue even if run while the network is down. 

Does anyone incurred in the same issue or found any solution? The phone is 3 months old...

[Rūmøur]

As you can see, you arent the first to face this issue. People have been facing this for months with no solution still.

https://eu.community.samsung.com/t5/galaxy-s21-series/s21-ultra-no-network-conection-after-the-last-...

[gpaolo79]

I know, I wrote in that thread before opening this one. I can't believe it's a hardware issue, it was the update that screwed up the phone. It's really unbelievable, a phone of this price and I can't make calls...

[Rūmøur]

Do you also receive an error when you try to manually select a network operator?

[gpaolo79]

I haven't tried that. But do you mean when the Sim gets reset? Or in general? I'm not sure I can do it during the failure, I have two sims, one in roaming and the other local. The local one has just a glitch, sometimes I don't even see the round symbol, or it stays there for one second. The one in roaming remains with the round symbol for a few seconds, but I don't think it's enough to do the manual selection of an operator.

[Rūmøur]

Go to settings and then connections, then to mobile networks. Select network operators and try turning off "select automatically"

[gpaolo79]

Ok, that is working fine, I don't get any error and I can register.

[Rūmøur]

Register on whatever mobile network that pops up that your carrier is also on. If you are able to successfully register, then I'm sure that's probably the end of your problems

[gpaolo79]

Ok, I'll try to set it manually and see what happens...

[Rūmøur]

Great

[gpaolo79]

Nope. I did set one manual to see if that one was working, but they have just both reset. I got an error saying that the network I had selected is not available.
So unfortunately this didn't do the trick...