I have faced an annoying issue with proper country detections of the clients in Ministra 5.6.1 (it is officially does NOT support geoip2), especially when it comes to IPv6. Even with up-to-date .dat file, converted from mmdb, ipv6 was still a problem. So I've ended up writing a patch to make it work with new mmdb format, without waiting when Infomir will decide to implement it.
Enjoy!