1st Sim card goes unreachable, when 2nd sim card is inserted.

[BakhtiyarAliyev]

Who has any idea what is happening?

1st Sim card goes unreachable, when 2nd sim card is inserted. Signal bars are on, but noone can reach the sim 1 number.

However right after calling from sim1, it become shortly reachable again.

I noticed, when sim2 is in 3G mode, all works. But it automatically jumps into 4G, as soon as I switch to it. And then again sim1 goes off, issue repeats.

Device: Samsung Galaxy s21 ultra, SM-G998BZSGMEA.

[Samsung_specialist]

Hello,

​Please follow the below steps:

Settings >> General Management >> Reset >> Reset all settings. And also, please check that both of your service provider support the required network.