Thanks for visiting the Community. My apologies for the late response here and I'm sorry you have to experience this. No worries, we'll sort this out. What Nest thermostat model do you have? Does the thermostat display show any error codes or messages? Can your other WiFi-capable devices (phone, tablet, computer) connect to the internet through your WiFi network? Also, how far away is the thermostat from the router?
Looking forward to your response.