Inspiron 15 5547 connects to network but not internet

Twice in one week my Inspiron 15 (5547) has refused to connect to the internet (no webpages, no email, no updates). It was connecting to the home network fine - with both wifi and Ethernet. Other computers and smartphones were connecting to internet fine.

The only way I could resolve the problem was to do a "System Restore." Then, despite saying that the restore failed, internet access was restored when system was rebooted. (Simply rebooting the computer would not resolve the problem by itself.)

I suspect some driver is being automatically installed that prevents internet access, or McAfee is updating and preventing access for some reason. Anyone else having this problem?