Here are a couple things you can try. I’ve listed them below from simple to more time consuming.
Forced restart takes just a minute or two and could resolve the issue. It’s much more than simply turning your iPhone off and on. I’m posting a link below with complete step by step instructions.
Force restart iPhone - Apple Support
Please contact Apple Support and request Remote Diagnostics and pay particular attention to the NFC module. If you’re in the US please call 1-800-MY-APPLE or outside the US, consult the support articles below.
Contact Apple for support and service - Apple Support
They can also do diagnostics at a nearby Apple Store Genius Bar, if more convenient. You can use the link below to make an appointment.
Genius Bar Reservation and Apple
Support Options - Apple