For the past few weeks, my computer does not keep internet connections properly.   After about 20-40 minutes on a network, I loose internet connectivity, though am still connected to the network. When I sign out of the network and sign back on, it resumes connection to the internet for another 20-40 minutes, then cuts out again. 

This happens on multiple networks, while others have no problem staying connected. (So the problem must be with my computer.) 

I have not changed my settings recently, so do not know why this problem popped up all of a sudden.

Any ideas?  Thank you. 

Are you connected via wire or wireless?

Have you tried updating or completely removing and installing the latest drivers?