Internet connection gone because of Norton?

Hi all
My pc can't connect to the internet anymore since a short time. I don't know why, because the internet is still working on my laptop and phone somehow. 
The only thing that changed meanwhile was Norton doing a defragmentation or something. I've read that Norton could block the internet connection, so I suspected that turning off AutoProtect would help, but it did not: my pc still has no connection.

What can I do to fix this?