Connected no internet

I've had this problem now for over 6 months with internet service - "Connected, no internet". I thought it was my Netgear modem being it was refurbished. (I also had a Netgear router "new" connected to this modem) I was reseting it multiple times a day. I finally went and purchased a new Netgear Nighthawk modem/router .. had the issue again..I had a technician come out and he replaced the line coming into my house and the connection outside. Everything was up and running again when he was here.. the next day it happened again. I spent a couple hours on the phone with Netgear customer service and we did troubleshooting option there was to possibly do to no eval and that agent said to return the unit back to the store.. that it was a faulty modem/router. I then disconnected this new modem/router and thought maybe I should go with a different brand.. so I purchased an Arris modem/router. Now I can connect my firestick on my one TV but my laptop still reads the same error. I called Xfinity again and explained all of this for the umpteenth time and said to them that I'm certain it's my internet connection and to please send out another technician (of whom will be out tomorrow). It would great to know if anyone else has had this same issue and corrected it.... PLEASE TELL ME WHAT YOU DID!! PLEASE!! This is driving me Absolutely Crazy!!