[Plugin: W3 Total Cache] Add support –

How popular is this server?

In august 2011 the company home.pl that uses this server had almost 2 milions of clients – usually every client has two web sites or more.

Do you have a link to their documentation? I didn’t find it after googling for a few minutes.

No, I do not have and I cannot find documentation.
When I complained about that error, they used to say that this is a php issue and gave me that link: https://bugs.php.net/bug.php?id=40479

Sorry, without documentation I can’t help further.