Generate ipv6 ips instead of a default one

[DorianCoding]

Checklist

• [x] I searched existing Issues, and did not find a similar enhancement request
• [x] This enhancement request is about the VPN setup script, and not WireGuard VPN itself
• [x] I read the README
• [x] I followed instructions to configure VPN clients

Describe the enhancement request It seems by default, the ipv6 range fddd:2c4:2c4:2c4::/64 is used. It would be better to get a random ipv6 range as described in RFC 4193. This is also critical if numerous Wireguards instances are created in the same VLAN, as the risk of address conflicts is certain.

It is also true for ipv4 but it cannot really be changed unless a random number is taken from 10.X ranges (which still gives 65 535 Ips for each instance).

Is your enhancement request related to a problem? Please describe. If many instances of Wireguard exists in the same VLAN, different machines would share the same ipv6 address.

Thanks.