NX Client 3.5.0 can get the following message when connecting to NoMachine 4 (free) or to any of the Terminal Server and Enterprise server products version 4:
 

The NX service is not available or the NX access

was disabled on host  ---.---.---.---

USE CASE 1: NX Client 3.5.0 is connecting to NoMachine 4 (free)

The client 3.5.0 connects to a server by SSH protocol and NoMachine login (public key authentication), while NoMachine 4 (free) supports only connections by NX protocol.

To be able to connect  with NX client 3.5.0 you need to install any of the NoMachine Terminal Server or Enterprise products v. 4 that  supports SSH connections.

USE CASE 2: NX Client 3.5.0 is connecting to any of the Terminal Server or Enterprise products

Possible reasons for getting message above are:
 

- The server supports SSH connections but it has been stopped, i.e. it doesn't accept new connections.

Be sure that the server is up and running, you can start it from the NoMachine monitor in your system tray: select 'Show the server  status' and click on 'Start the server'.

- The server supports SSH connections but it has been shutdown, i.e. all NoMachine services, included the Monitor in the system tray, have been stopped.

Be sure that all NoMachine services are up and running, you can start them from the NoMachine GUI: click on the 'Show the server status' button to open the Server Status panel and click on 'Run the server'.

- The server supports SSH connections but they are disabled in the server configuration.

Be sure that SSH is listed in the ClientConnectionMethods key in the server.cfg file (e.g. ClientConnectionMethods NX,SSH,HTTP). Restart the server, even from command line or by Server Status GUI by clicking on 'Stop the server' and then 'Start the server'.

- The server is not installed. 

Install any of the NoMachine 4 products on your server host machine.

Note

If you are still using NX Client 3.5.0 to connect to NX Server 3.5.0 and you receive the following message:

"The NX service is not available or NX access was disabled on host"

it is likely that the NX server is stopped. You should check the NX Server status by running  the command from a console as root user:

# /usr/NX/bin/nxserver --status

If the server has stopped, you should get the following output:

# nxserver --status
NX> 900 Connecting to server ...
NX> 204 Authentication to NX server failed.
NX> 110 NX Server is stopped.
NX> 999 Bye.

In this case, just run.

# nxserver --start
NX> 122 Service started.
NX> 999 Bye.

You should now be able to connect.