Welcome to our world, a year+ of trying various solutions to this pervasive issue since upgrades to Windows 8.1. Commonalities--same old router in most cases, working well on all other Windows OSs except 8.1. No change in location or anything else, but computers w/8.1 have dropping off. So...
After many, many other fix attempts, I finally went into my Device Manager, selected the Network Adapter I’m using, then selected that it was NOT allowed to be turned off to save power.
**That did it.**One of the other fixes may work instead for you, but I’d try this one first. If it's your issue, too, it will save you a lot of frustration. I was getting ready to buy a Mac!
Diana