[Jake187]

OVH anti-ddos is not built for games, the UDP protection is built by a default UDP rate filter to protect against all UDP floods which is not made for certain games meaning someone can still attack with certain amount of packets each time and cause your game server to stress. This can only be done if they have the actual access to a botnet and the ability to decide how much packet size should send, this is not the easiest thing to get access to and therefore it's not the most common attack unless a experienced attacker attacks.

The only way to overcome this on OVH is to get their game protection which is offered in their game ranges at the following links
http://www.ovh.ie/dedicated_servers/game/ and https://www.soyoustart.com/us/game-servers/ this will limit the packet rate to the actual game rate which is far less than their actual rate for the default UDP protection.