OVH has a lot of quirks. Being that they own all the lines that the hosts run on, they get to call the shots on how to best setup their system. In order to keep their networking infrastructure as is, they have opted to go a route that means you're working with custom OVH kernel headers. I think the more costly move was to upgrade their infrastructure, but that didn't happen so now people have to deal with their quirks.
Another thing I noticed was their lower tiered VPS (non-cloud) would be upgraded one host at a time. That means you could have two VPS with them, and have considerably different performance and set of issues to work with when dealing with identical software.
I'm curious, which package do you have with OVH?
I have heard of issues with OVH until you get to their dedi and expensive cloud options. Even a soyoustart dedi has serious networking issues. I have a friend who purchases these specifically to test out clients getups before throwing them on production gear elsewhere. Because they throttle and have a very poor network reliability at this tier, it makes a great test-bed to show the bugs in a system design within a limited time-frame.