There is an issue with the Battle.net client going to sleep since the last Win10 Update. Deleting the Data file doesn’t fix it. Fear not, if you launch the game you want to play out of the retail file for it, you can play. I know this works on Overwatch, and saw reports that this is working for starcraft as well. Make sure to select the games .exe, not the game launcher. You will need to log in with your Battle.net from the game.
C:\Battle.net<The Game you want to Play>_retail_
Just a work around, until Blizzard Updates the client, hope this helps!
MAKE SURE YOU CLICK ON THE GAME EXE, NOT THE GAME LAUNCHER EXE. THE GAME LAUNCHER EXE GOES THROUGH BATTLE.NET, THE GAME EXE DOSE NOT.
I am literally playing OW, so it works for that. I can open COD:MW, not sure about online for that though.