Hi @Kdmcright
The following could be at fault.
- Phone.
- Sim card.
- Network / Cell Masts.
- An app is causing conflict.
In regards to the phone. > Reset the network connection in Settings, General Management, Reset,Reset Network Connection and then see what happens.
As a process of elimination try your sim card in another phone and then see what happens. If you can try another sim card in your phone.
There is a diagnostic tool in your Samsung Members App to check out the phone.
A Samsung Experience Store or Samsung Service Centre can check out the phone.
In regards to the Sim Card > Try the sim card in another phone as a process of elimination. Your Network can replace a sim card sometimes called a Sim Swap.
In regards to the Network / Cell Masts > Check your local and surrounding Masts by using any relevant network mast checker your network may provide online. If this happens everywhere you go however then this rules out network issues.
In regards to An app > https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ turns off downloaded apps and themes etc which may highlight an app or theme that's causing conflict. > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
If the Sim card and Network / Cell masts are fine and the phone is displaying this everywhere you go and your within any relevant cooling off period then have the phone swapped out.
If your past the cooling off period then a Samsung Experience Store or Samsung Service Centre will need to diagnose the phone.
I wish you all the best. 
