If you don't have HostKey for Ed25519 generate it:
# ssh-keygen -t ed25519
You need to use recent version of ssh / pyTTY to be able to login to this server.
It seems that using only this Cipher/Kex filters all brute force scanners probably because they do not support it. I see only this kind of messages:
Feb 13 14:41:39 horizon9 sshd: SSH: Server;Ltype: Version;Remote: xxx.x.xx.xxx-53810;Protocol: 2.0;Client: libssh2_1.7.0
Feb 13 14:41:39 horizon9 sshd: fatal: ssh_dispatch_run_fatal: no matching cipher found [preauth]
More information about ciphers/algorithms read here: