Connectivity issue

Reset network Settings and than restart the phone.

Dear Samsung member,

Greetings from Samsung customer support.

We acknowledge your query and apologize for the inconvenience caused to you and will surely assist you regarding the same and please follow the easy troubleshooting steps which might help to solve the issue.

Kindly restart your smartphone once and also re-insert your SIM card.
Check device network in an open area: Kindly check your device in a different location/network coverage area.

Check device network mode settings
Please follow the below steps.
Step1: Navigate to the app's screen and tap on Settings.
Step2: Tap on Connections.
Step3: Tap on Mobile networks.
Step4: Tap on network mode SIM1 or SIM2.
Step5: Select network mode.
Note: We recommend setting device network mode as LTE/3G/2G (auto connect) mode.

Kindly do check the same SIM card in another phone or another SIM card on the same phone to verify the issue.

Please visit this mentioned link to resolve your device issue: https://www.samsung.com/in/support/mobile-devices/how-to-prevent-the-overheating-of-your-galaxy-device/

In case the issue still occurs. Please register your concern in Samsung Members Application (Open Samsung Members Application > Support> Tap on error report > Type your query > Send).

Thank you for writing to Samsung.

Warm Regards,
Samsung Customer Support

I had this issue on my S24 ultra where one sim was not able to get a network on dual sim mode because my 1 sim supports 5G, and the other one supports only 4G. We are not able to select Mobile Network Mode from the setting.
To fix the issue, I have used the'Force LTE only' app from the Play Store and selected GSM/WCDMA preferred.