OVH is cheap but their anti-spam/abuse departments are ineffective. Too often they do not action blatant spam reports so in effect OVH is part of the problem with network abuse on the Internet. I've had to blackhole many of their netblocks while the people who run mxroute (solid email providers) have written about doing the same.

OVH needs to clean up their act.

HAProxy has some really good features a server admin can use locally without sending all of our data to Cloudflare or OVH.
https://www.haproxy.com/blog/application-layer-ddos-attack-protection-with-haproxy

There are many protection modules for most reverse proxies that provide basic (limiting) or sophisticated (captcha, calculation challenge, etc) DDoS protection. HAProxy is just a very powerful and easily extensible proxy.