My friend has been telling me (She recently updated to Windows 10) that they've created a new virus protector. Games like FH are not compatible with Windows 10 apparently. Although this might not be true (I don't have it because I don't really like the sound of Windows 10). Maybe there could be a way of removing this virus protector and I hope someone who does know how to help you replies because I'm not quite sure how to disable it! Hope this helped! (:
Windows 10 is just a new fancier and improved Windows 8 with a few more new gadgets and interesting things.
Like mentioned above try getting a new anti-virus or a suited one to Windows 10 (really, anything should work, Windows 10 is literally a more organised template for office work if anything).
Also be sure that your firewall/anti-virus is not blocking the game, I know with some anti-viruses, they like to do just that and quite frankly it's annoying indeed.
But give it a try, make sure nothing you've done at the start of installing Windows 10 has effected anything, maybe even check online to see if Windows 10 has any tips for you and your online gameplay experience.
Goof luck to you, Caerulus~