Please verify that the SSH fingerprint is correct. Your SSH client will likely ask you to do this on your first time connecting.
These are the correct fingerprints for Ahti as of 2018-11-21.
SHA256:hSFgRenCdwRl4mWz9XVsj56Do4hB+4SM5R0qArAAY44 (DSA) SHA256:V9Ek9DOR/lEPzuDOLSTqWKnsNPo05I3U5SJi6e0E/3A (ECDSA) SHA256:s5THA0KpSDCVtxRRCopLBouBtWufVAHnoPf0xslAtRY (ED25519) SHA256:M7B9iy9a/kwVD/1nZ1JlzC6Fs9faDAvS3ZEs23DSHEU (RSA)
If your SSH client doesn’t support SHA256 fingerprints, please poke its authors. But for the time being you can also use these fingerprints.
MD5:e3:ae:6e:44:42:68:6f:66:61:37:c7:0b:55:3e:ac:18 (DSA) MD5:ac:54:51:d8:1f:0c:a8:43:c0:d7:82:97:d0:55:1c:47 (ECDSA) MD5:7d:4f:80:a3:8e:5f:2f:8f:48:d3:6b:53:2a:32:d3:4f (ED25519) MD5:cf:6b:7b:46:95:41:72:ae:ab:0b:7a:bd:af:9b:48:04 (RSA)