Hey there Snmartin13,
For our own iPhone 13, it shows what you described for our cellular carrier at the top left corner in the Lock Screen, but it does show the cellular signal strength at the top right corner. We also see the '5G' logo at the top right if we're not connected to Wi-Fi already from the Lock Screen.
With the above in mind, it seems as it the issue you're having is that you're not seeing your cellular signal when disconnected from Wi-Fi(along with not showing the cellular strength), from the Lock Screen. If that's right, we want to confirm are details to better understand what's happening, along with ruling out some possible causes:
- Are you seeing your carrier name, along with the cellular strength, after unlocking your iPhone?
- When was the last time you saw both the carrier name and cellular strength on the Lock Screen?
- Sometimes unexpected behavior can be resolved with a restart: Restart your iPhone
- We see you have iOS 11 installed on your iPhone 6, but the latest version for your model is iOS 12.5.6. You can verify this within Settings > General > About. In case you needed it, this link shows how to first back up, then Update your iPhone or iPad.
Cheers!