Mosh hangs during connection to the server in AIX

Hello community members,

We are experiencing an issue where Mosh hangs during connection to the server in AIX using the command:

mosh root@server_name

The connection proceeds correctly when connecting to localhost or to remote systems without password protection—in these cases, the Mosh session starts successfully, and we can see the shell prompt.

However, when attempting to connect to a password-protected server, the session hangs with no further interaction possible.

The process tree is as shown below:

#proctree 20382124
2687330    /usr/sbin/srcmstr
   9371960    sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups
      19136866    sshd: root@pts/4
         20185538    -ksh
            14877164    bash
               20119814    perl /opt/freeware/bin/mosh root@aixoss1-lp8.pok.stglabs.ibm.com
                  20382124    ssh -n -tt -S none -o ProxyCommand='/opt/freeware/bin/mosh' '--family=prefer-in
                     13893910    perl /opt/freeware/bin/mosh --family=prefer-inet --fake-proxy -- aixoss1-lp8.po
                        19202338    perl /opt/freeware/bin/mosh --family=prefer-inet --fake-proxy -- aixoss1-lp8.po ```

Start by reproducing mosh root@server_name on AIX against a password-protected server and compare it with localhost or an unprotected server. Use the provided proctree output to trace where the SSH and Mosh processes stop; done means the connection completes and displays the shell prompt.