I see many people in this forum with a similar problem so I decided to post this here.
I've had this issue where I could only do the story mode and the 1v1 duels.
As soon as I tried to join a 2v2 game or any of the 4v4 game modes, it couldn't find a match, it decreased the matchmaking filters but it keeps going without success.
If you have this issue you were probably an alpha/beta tester.
I was checking the files of the game and I noticed that multiple files were still from the beta and some of them even from the alpha.
Follow these few steps to fix:
- Go to the ...\Ubisoft Game Launcher\games\ForHonor folder
- Sort the files by date
- Delete all files and folders downloaded before 14/02/2017
- Go to uPlay and select the game
- Go to Properties
- Click 'Verify files'
- When done scanning, click 'Repair'
I hope this helps some people like it did for me,
Enjoy the game :-)