My IPhone 8+ Signal Not Working while my Service is Active/Payments are Up to Date???

Hi my iPhone 8 plus and recently within the last day started having very strange issues regarding having just a little service like one bar, and then in the next two minutes or so then switches toNo service, and then to roaming… I’ve restarted and refreshed through airplane mode as well and it is only allowing me to use data in WiFi range. If somebody could please help me understand what it is so I can fix it, I’d greatly appreciate your help. Oh and also my SIM card I tried taking out n cleaning off but still same issue…