Thanks Rajan. It looks my issue is different. There it is connection refuse but mine is unknowhostexception.
Please suggest how it will help.
Use the --no-certcheck tag at the end
tabcmd login -s <Servername> -u <username> -p <Password> --no-certcheck
Hope this helps kindly mark this answer as correct or helpful so that it will help others
I tried the same but it did not worked out.