DUAL SIM issue since One UI 4 update

[Drazuhl]

Hello,

I've  had a big issue since the update with my network.

Any time I'm outside (with no Wifi) even if there's good 4G coverage, I randomly (and sometimes constantly) lose network on both my SIMs (both from the same provider).

I'll try to use internet, then I'll get the "forbidden" logo on both SIMs for a few seconds instead of the network bars (the Airplane mode symbol will also look like it's activated for a short while), then the SIM will show the normal bars for a while, sometimes Internet works then, other times it just repeat the same cycle.

I've ended up completely unable to use internet at times.

Here is a Video of the problem 

I've tried many things, changing different settings in the SIM section, resetting the network settings, forcing reboot (volume + ON/off button),...

I've realized that when I deactivate one SIM (either one), I do not have the issue with the other SIM, so this seems to be related to dual SIM, but they were working just fine before the update...

Can anyone think of a reason why this is happening? I really do not want to factory reset / send back my phone...

Thank you

[Roy1076]

I'm having the same issue  just upgraded to android 12 today and after that one line send all the incoming calls to the voice mail. The other sim worked just fine. I switched the Sims and found that the issue is the sim #1. It's ok to know I'm not the only one with this problem but not nice to have to wait till samsung fix this bug. In the mean time I have a line out of service!!

[S21-User]

I also have very similar issues after installing the June security update on my S21 with Android 12. When I enable both SIMs simultaneously, they don't receive calls anymore. Each on its own works fine and also in either SIM slot. To not miss calls, I can only use one SIM. A factory reset did not fix the issue I have not found a way to uninstall the update. 

@Samsung - please help!