Thank you for using Apple Support Communities.
I see that you are getting a "no service" notice on your iPhone 7 Plus. Your troubleshooting includes a network reset and at the suggestion from Apple Support, a software reset. All without success.
I would suggest taking a look at the following support article for no service issues with the iPhone. I know you have tried several of the steps from this article, I would ask that you bear with me and follow the steps as outlined to make sure that nothing is missed.
If you see No Service or Searching on your iPhone or iPad