Any error messages? Any known hardware or software changes: some update maybe?
Go into the Network and Sharing Center or otherwise find and run the network trouble shooter. See if that can identify and fix the problem.
You can also run Task Manager and look at the Processes and Services that are running. Note anything running continuously with a high % of use. "High" being a bit relative as we do not know what is "normal" Whatever is running is consuming laptop resources which, in turn, will slow down performance. Could be some program trying to "phone home" and failing because of a network problem.