OS X Sierra wifi/internet issues

I upgraded to OS X Sierra two days ago, and I haven't been able to get wifi/internet to work for TWO days now. It connects to the network just fine, but there is virtually no internet connection. Every once in awhile a page partially loads but then stalls out. And simultaneously I'm using my OS X Yosemite laptop and getting 80mb down internet speeds on the same network.

There are numerous articles online about wi-fi problems with Sierra installs, and I've followed what most of them say, to delete existing wi-fi preferences - e.g. files at /Library/Preferences/SystemConfiguration/ http://osxdaily.com/2016/09/22/fix-wi-fi-problems-macos-sierra/

So this is a known issue, but I can't find anywhere Apple acknowledging the issue, or providing a solution. Am I missing something??