Unable to establish an internet connection.

Circa 13" MacBook Pro, OS X 10.9.5 - Networks to everything but the interweb. Problem started about a week ago. Other machines (iMac, iPhone, iPod full bars) access it no problem. Went through Network, Assist Me, Diagnostic... Network Status shows green dots for Wi-Fi, Wi-Fi Settings, Network Settings, ISP. But Red Dots for Internet and Server (failed). Go through 'Continue' in the usual way and then the 'Allow/Deny' window pops-up. (Allow). All green dots... works correctly... for about 30 seconds... then Red Dots for Internet and Server (failed). No other devices are sharing. Did the PRAM and it worked for a day then right back to this again. Tried Preferences; no go. Direct plug-in to modem; nothing. Another location; nope.

The one thing that I find odd is in Advance. 802.1X (Profile Information) is all blank whereas in the iMac, it's filled out.