i2p router mostly shows: Network: IPv4: OK; IPv6: Firewalled i2p supports UPnP. Is this UPnP for IPv4 only. Or also UPnP for IPv6 ? UPnP only works with IPv4 as IPv6 generally does not need ports to be forwarded. If your connection supports IPv6 you may need to open the port used by I2P for IPv6.