Every dedicated server at Strato can get an /56-IPv6-Subnet. Just activate IPv6 support on the control panel of that server and you will be informed about your subnet and the primary address of your server.
# configure address
/sbin/ip addr add <main ip address> dev eth3
# set default route
/sbin/ip route add default via fe80::1 dev eth3
In case everything was configured correctly you can test it with:
# ping6 -c5 ipv6.google.com
PING ipv6.google.com(ham02s11-in-x13.1e100.net) 56 data bytes
64 bytes from ham02s11-in-x13.1e100.net: icmp_seq=1 ttl=56 time=6.79 ms
64 bytes from ham02s11-in-x13.1e100.net: icmp_seq=2 ttl=56 time=7.24 ms
64 bytes from ham02s11-in-x13.1e100.net: icmp_seq=3 ttl=56 time=7.28 ms
64 bytes from ham02s11-in-x13.1e100.net: icmp_seq=4 ttl=56 time=7.28 ms
64 bytes from ham02s11-in-x13.1e100.net: icmp_seq=5 ttl=56 time=7.28 ms
--- ipv6.google.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4006ms
rtt min/avg/max/mdev = 6.793/7.177/7.287/0.213 ms
If you want to keep that settings permanently, put all command it /etc/rc.local
So there seems to be no problem with stand alone servers at Strato.