SSH banner exchange: Connection to UNKNOWN port 65535: Broken pipe

Not sure why this happens, but when I try to use a proxyjump command, this error comes:

$ ssh login2jet2
/bin/bash: No such file or directory
banner exchange: Connection to UNKNOWN port 65535: Broken pipe

the relevant ssh configuration is:

Host login2jet2
        Hostname jet02.img.univie.ac.at
        User USER
        ProxyJump aurora.img.univie.ac.at

This used to work on previous distro (Manjaro, Arch, BlendOS, Ubuntu, RockyLinux, ...) but now with NixOS it fails!?