@Brunocerous That's a rather unusual configuration, but it makes sense that you wouldn't be able to connect if you only have an IPv6 address. Both AresCentral and Gray Harbor are hosted on Digital Ocean, and they do not enable IPv6 by default.
I'd suggest asking the person who controls the network at the house you're staying up how you can get an IPv4 address. You can also double check that you don't have an IPv4 address at: https://test-ipv6.com/ The first line SHOULD read: Your IPv4 address on the public Internet appears to be ###.###.###.###.