This means that the news client cannot reach the server.

First check whether the server address in the server settings is correct.  You may need to delete the server and create a new one.  If this does not help, the problem is probably not due to the settings of the newsreader.  Perhaps there is software blocking the connection, such as anti-virus software or a firewall.  Temporarily deactivate this software and try to establish a connection once more.  Also, check for a possible firewall in your router or modem.

Sometimes the newsreader needs to be re-registered in the firewall after an upgrade of the security software as the firewall might have assumed a virus has entered modifications and blocked all traffic.

Attempt to establish a connection with a different newsreader to rule out that the problem is due to the utilised newsreader you are using.

Perhaps the DNS server of your Internet provider is temporarily not working correctly.  Check whether the DNS server settings on your computer are correct and match the details of your Internet provider.  In order to correct the DNS problem, you can enter the IP address of the server in the server address line.  See the Service Status for the correct IP address.

NOTE: The IP address of a server can change over the course of time.  This can potentially cause you to experience problems.