el capitan - macbook pro - wifi connects - no internet - isp failed

Hi.

After upgrading to el capitan this morning on my macbook pro, the laptop is refusing to connect to the internet. It worked for 5 minutes, then collapsed.

I have been troubleshooting, network diagnostics, rebooting modem, deleting files in systemconfiguration (it wouldn't delete all), restarting the laptop... I can find no more solutions on different forums.

But the problem persists.

ISP failed.

iPhone 6 pluss (iOS 9.0.2) and iPad connect to the internet just fine.

Can you please help me? I need internet to function :/

rianne