[RUST] Can't connect to Rust Server with IPV6 Address

For the first time connecting to Rust Server (EU CENTRAL) via Steam I used an IPv4 Address. That worked fine. Then I changed my IPv4 to an IPv6 Address. After changing to IPv6 I can’t connect to the EU CENTRAL Server anymore. But I can still connect to EVERY other Server except the EU Central :frowning:
And NO, I can’t change back to IPv4.
plS Help?^^
best regards
Schlumpf <- Ingame Name