I'm not going to be adversarial here, nor am I going to beat around the bush.
A few weeks ago I had a issue where my nat type had gone to strict, whereas the litteral hour before it was open. Such is the case today. I played with a open nat type yesterday, and today it is strict.
Before, we fixed it by uninstalling Uplay and For Honor alltogether, then re-installing them, but I am not doing this ever few weeks and given it seems to be replicateable, I'd surmise that it is on the end of the publisher/developer.
I like you guys, I like this game, even though it makes my blood boil, but call me when you get this sorted out. If you have any information you need I'll be watching the thread for a little while.