[sagher]

It's nothing to be "disclosed" or "revealed". It's just that they enabled Permanent Mitigation. It looks like you were receiving OVH-Bypass based attacks from some paid booter website, which wasn't mitigated due to the nature of delivery and transit. If perm mitigation or VAC is enabled, they're heavily filtered and that's why it stopped. Generally, if there is an attack, OVH would automatically enable VAC, which would then stop attacks but if the packets look legit enough, there is no need to enable VAC. If enabled permanently, all packets are scanned before they're allowed to pass. This is what I love about OVH.

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"Unmetered" is a vague term. If any provider says "unmetered", it means we'll ignore how much you use the resource BUT if its sudden, or if its too heavy for our main node, we'll stop it. So yea, mostly unmetered to have limits secretly imposed. Those limits can be removed by request or special mechanism which would allow further resource based on request or legit use.

And no, get yourself that 100mbps server if DDoS is your concern. A protected server must be a priority for those running gameservers or such which are DDoS-magnets. Otherwise, if it's closed corporate management, or a small organization which isn't under attack, then why not?

Thank you @Manal for your detailed feedback. i am on same page as you that unmetered doesn't mean that you totally free to make maximum load on virtual machine. 
So my opinion is to providing DDos Protection with unmetered machine is much more reliable specially if we make a gameserver.