Since few days, the Feed/RSS http://www.mydomainname.com/feed is considered as a 4040 Page not found.
I used the version of YOAST plugin before 1.4.13, i deactivated it then activated it and the problem of the Feed has gone. RSS displayed well again.
I upgraded 2 days ago to YOAST 1.4.13 and the same problem again. Without notice or reason, the feed page is considered as a 404 not found PAGE. I am obliged to deactivate and activate again the plugin to recover a correct feed.
I let you realize the lost of productivity as nothing is fed to social media from our Feed/RSS.
Now i have to check permanenty that feed is OK. Even Google Adsense displays errors messages.