No telnet,
Do it the following way.
- create a normal status host with ping and one active check - “Check connecting to a TCP port” with port 6557
- test if this is working
- now change the host check command from ping to “Use the status of the service …” now insert here the name of your TCP port check like it is in your GUI
- now check if the host shows down if you livestatus on the slave is stopped
- if this is working you can use this status host inside your distributed configuration