Xfinity mobile showing no network available on Motorola g7 power

I recently added my husband to my xfinity mobile account. I have zero issues with xfinity mobile on my samsung galaxy note 10+ and my mom also has zero issues with her iphone 8. He got his phone, a Motorola g7 power, and a new SIM in January. His first phone wouldn't charge so we got a replacement in May I think. Since then, his phone will show "no network available" and he can't make or receive calls, texts, or mobile data. Sometimes a phone restart will help, other times it needs restarted multiple times to get any kind of network back. This will happen typically every 2-3 days.
He is part owner of a trucking company so he uses his phone to make phone calls between the drivers and he needs it to work all the time. At this point, he's ready to ditch xfinity mobile and go back to Verizon where he had no problems.

Could it be the phone since it's just since we got the replacement?
Could it be the SIM? When we got his replacement phone, we were sent a new SIM card that I was considering trying in place of his old SIM.
Any ideas what else it could be? I don't think it's the network since I can be sitting right beside him on a phone call and his phone shows "no network available" and unable to make calls or send/receive texts.

I'm just frustrated with this whole thing and looking for a way to fix this.