Logging into the SSH console in CA 2.1 results in sudden 'Server closed connection' message after authentication.

SSH clients PuTTY 0.68 or higher, and macOS Sierra, send the IUTF8 (RFC 8160) terminal mode by default, which CA 2.1 rejects and resets the connection.

Older SSH client versions work due lack of utilization of the flag. Other SSH clients such as MobaXterm and BitVise also work.

PuTTY 0.69 introduced the ability to change the tty flags. You can disable from the SSH > TTY configuration.

You may also modify configurations of OpenSSH to not utilize the flag (*nix/BSD) or use a third party client.