Could be many different problems, but "CCleaner" is a decent freeware utility that will clean up a lot of the most obvious junk that accumulates. Will also clean up your registry.
It's worth learning about basic router and internet security. The people who service computers have no incentive to tell you how to avoid having to hire them again and again to fix largely preventable problems.
I've used this program for years with great success and minimal cost. I use Windows7 and the lack of future updates is irrelevant: one reboot and problems solved.
Like many of the best ideas that threaten "stakeholders" it is largely ignored in the mainstream, but the corporate & institutional clients obviously know what works.
Windoze10 is probably no more secure than Windoze7 and why bother to learn to navigate around a bunch of crappy new interfaces for no real gains?
The privacy state of Windoze10 is comical, when not simply creepy.
Welcome to the brave new world!![]()