On most of the newly installed windows server the telnet client is not enabled.

If you want to test if a remote port is open you can use a powershell command:

PS C:\Users\angelo> test-netconnection -ComputerName server.domain.local -Port 8403

ComputerName           : server.domain.local
RemoteAddress          : 10.10.10.30
RemotePort             : 8403
InterfaceAlias         : Ethernet0
SourceAddress          : 10.10.10.24
PingSucceeded          : True
PingReplyDetails (RTT) : 1 ms
TcpTestSucceeded       : True