MQRC 2538 means "host not available". Check the host name and port name that you have specified and is pointing to the machine where MQ queue manager "MQSERVER" is running.
Check on which port your queue manager is listening. You can do that by using MQExplorer or runmqsc command shell on the machine where you queue manager is running. In a command prompt, run the following command
runmqsc MQSERVER
Once the runmqsc shell opens run the following command to list TCP listener.
dis listener(SYSTEM.DEFAULT.LISTENER.TCP)
Check the PORT number displayed. By default it will be 0. You need to change this to some port number. To change the port number run the following command.
alter listner(SYSTEM.DEFAULT.LISTENER.TCP) port(1414)
Once this is done you need to start the listener by running the following command
start listener(SYSTEM.DEFAULT.LISTENER.TCP)
After this you can attempt your tests.