For the last few months, since I've upgraded to One UI 5.0, my phone has been losing mobile signal when I leave my home wifi. For instance I leave my home wifi, go outside and I have no mobile signal. I try toggling the mobile data on and off, still nothing. The solution that works is rebooting the phone. This also happenes while I'm on a train entering and then exiting a tunnel. I have no idea why this is happening, and this has only been occuring since the ONE UI 5.0 update, and it's extremely annoying. Is there any other solution than rebooting my phone to keep the mobile signal constantly working?
Try getting a new Sim card. I had an issue like that when I had my iPhone. When I went from wifi to data it wasn't working. In my case verizon said it was an old and rare Sim card error
If you continue to lose the data connection, you will need to reach out to your service provider for additional assistance.
In the event, the service provider is unable to resolve the network concerns, it is recommended to have the phone evaluated by an authorized service center. You can use the following link to find a list of service centers in the U.S. that can do the repair: http://www.samsung.com/us/support/service/location or by contacting customer support at 1-800-726-7864.
Samsung offers a variety of repair locations, including walk-in Samsung service centers. Select the product that needs service to find a location near you.
