No calls on Apple Watch SE standalone

@Fi0na 

Due to the watches small size it has nowhere near as good an antenna as a phone. Losing connectivity is an unfortunate side effect of having a poor antenna. It also tells me you're not in the best coverage area.  You might want to consider getting your child a flip phone if they are old enough

Thanks for getting back to me. 

That’s sad to hear that. However, my mom’s iPhone has the same issue while me and my husband’s phone are fine as we are in the same family plan and live in the same area. I thought that must be something is not right. 

@Fi0na 

Might it be a 5g issue?   Does mom have an LTE only iphone?

No.

Thanks for all the replies. I updated the IOS systems on watch & my mom’s phone, so far so good. I think it might just because of the outdated iOS system. 

That'll do it! 

One thing you can try is to reset your watch by pressing and holding the side button and Digital Crown until the Apple logo appears. You can also try resetting your network settings on your iPhone by going to Settings > General > Reset > Reset Network Settings. If these steps don't work, I would recommend contacting Apple support or your carrier to see if there are any known issues with your device or plan. They may be able to provide you with further assistance or suggest a solution.