Piwik fails to recognize IPv4-mapped IPv6 addresses and GeoIp lookup fails because a plain IPv4 address is expected.
It seems to be enough to remove the initial '::ffff:' string.
Thanks for the report & patch! :)
@Capedfuzz please check patch looks good and if it needs to be applied in other places.
(In ) Fixes #3458, fixes #3515, improved geoip diagnostics/help & allowed IPv4-mapped IP addresses to be geo-located.