Segue abaixo um exemplo simples para validar a conexão com um servidor / serviço remoto.

[root@lab ~]# nc -zv 10.13.40.10 3389
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to 10.13.40.10:3389.
Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.

[root@lab ~]# nc -zv 10.13.40.10 33980
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connection refused.

Abs!