Hi, so I had similar kind of message then 403 forbidden status, when I first upgraded to cloudflare. But then it connected fine after about 10mins, I am using Google domain not sure about ovh, hopefully Peter can help you out. Or check this post:
This server could not prove that it is **www.gratisland.fr** ; its security certificate is from **ssl967779.cloudflaressl.com** . This may be caused by a misconfiguration or an attacker intercepting your connection.
