Is it expected that Mikrotik device listens on TCP port 51922 and shows following banner: SSH-2.0-ROSSH, when connecting to that port?
if you changed default ssh port and allow connections in your firewall, then yes
but without your config we can only guess
Thank you. Does Mikrotik devices come with ROSSSH installed?
Where can I change SSH port?
SSH-2.0-ROSSH means “RouterOS SSH”, it is part of RouterOS.
SSH port can be changed here: https://help.mikrotik.com/docs/spaces/ROS/pages/328229/IP+Services