Access server via IP v6?

Solution 1:

IPv6 is not just another way to write IPv4 addresses, and you cannot convert between them as you've done. A server that does speak v6 will have a v6 address that is quite different from its v4 address. For example the host orange.kame.net has the v4 address 203.178.141.194 and the v6 address 2001:200:dff:fff1:216:3eff:feb1:44d7.

To successfully use IPv6 you need either support for it from your ISP (unusual, unfortunately) or a device that does tunneling for you. The later is built in Windows 7, Mac OS X, and a few other OS:es.

Solution 2:

Or might that be because of my server or ISP not supporting IPv6 ?

Yes, absolutely. Either your ISP has to support IPv6 natively or you setup a 6in4 tunnel with one of the known tunnel brokers (e. g. http://tunnelbroker.net/).