Note: I wrote this up as a reply but the parent was deleted in the interim so posting at the top level instead.

> Which server is this? A Whois lookup returned nothing.

The whois command works on domain names, not IP addresses.

To get the DNS name associated with an IP address you can try a reverse lookup:

    $ dig -x 185.100.87.84

Unfortunately that only works if the the reverse record has been set up and it hasn't in this case.

You can still see where the server is located via tracepath:

   $ tracepath 185.100.87.84
    [truncated]
    12:  lon-tel-01c.voxility.net                             86.537ms asymm 16 
    13:  buc-ird-01c.voxility.net                            147.516ms asymm 17 
    14:  buc-ird-27sw.voxility.net                           136.914ms asymm 18 
    15:  buc-ird-46sw.voxility.com                           149.699ms asymm 18 
    16:  185.100.87.84                                       143.626ms reached

So most likely the server is hosted on voxility.com which looks like an IaaS provider.