WI-FI drops out every 5-10 minutes

Hello,

    I have internet provided through Xfinity and have an Xfinity modem. Two days ago my wifi started dropping out for 1-2 minutes every 5-10 minutes. This is for all devices on the network. Interestingly, my desktop, connected directly through ethernet, does not face these dropouts. All attempts to restart the modem to fix the problem have failed. My favorite so far is a customer service representative through the chat directly telling me twice that he found the problem and that it is "definitely fixed for sure", only for the problem to happen immediately afterwards.

Please help!