and what kind of service is your server providing ?
is it http ? (then use a http get action)
is it udp protocol ? (there is a udp send , though the reply back is another thing .....)
... etc.
you should tell more in order to check the service that the server provides
or alternatively
instead of checking the server (this is different than the service !!) as you want to do now by use of telnet which is a security danger (very big)
then
why not install a simple http server (there are a ton available, even can have a tiny one with python) and test it with a http get action