CHROMEBOOK connected but cannot log-in or browse

My Xfinity network has been working fine. 

My son just brought his chromebook over and he cannot browse (and now cannot log into chrome).  Using the xfinity app, I have confirmed that the device is connected to our network.  I have tried resetting the gateway and modem several times to no avail.  For some reason we cannot browse.   When we went on as a guest to by-pass chrome sign-in issues, we still cannot browse.  At times we get a "no network" or "DNS error" response.  any ideas?