Dual sims both stopped working S21 ultra

[soleilombre]

I can't access the sim card manager or mobile networks at all on my phone! It doesn't recognize sim cards. I get no mobile signal any more.

I have an S21 ultra dual sim. I was traveling internationally and had the sim 1 slot turned off in the sim card manager so I didn't incur roaming charges. When I landed home I opened the sim card manager and turned off the sim 2. Normally this automatically turns on the other sim card. But it flipped out and exited the sim card manager. So I effectively have both sims turned off and get no mobile signal at all 😞

I tried to reload the sim card manager but when I tap it, it either does nothing, tries to enter the sim card manager and then exists before it can load anything, or gives me an error message related to call settings. The only way for me to load the sim card manager is to take both sim cards out. Otherwise it won't load it it gives an error.

Note: I hadn't opened the tray to swap physical sim cards in about two weeks.

Does anyone know what's going on or how to get my sim card slots working again?

Things I have tried:

- Multiple resets

- swapping out sim cards

- swapping which sim card was in which tray

- doing a reset in all network connections

- booting into safe mode

Anything else someone might be able to suggest to fix this issue?

[Miri22]

Somewhere else I've read this as a solution: to go to the app of the esim and uninstall it in the app, and then try updating the phone. I tried this, and updated my phone, and afterwards I could access the sim manager again. I selected my main sim, and strangely enough I could still use the esim for data and calls. So that's how the problem was fixed for me.