Internet Connection Issues

We've been an Xfinity customer for at least 3 and a half years now. We have never had an issue until now. It's been going on for a week. We have been having issues where the internet cuts out every now and then. It will say "connected, no internet". We can't trouble shoot because when I open the My Account app, it says that our modem is unresponsive. We have tried everything. We have contacted the customer service multiple times and they can't seem to help us. We have moved the modem to different places and even unplugged everything. Please help.