Connect a computer fails and/or shows offline

Some PCs show offline in the the Dashboard. If uninstall the connector from the client, reboot, and try to recconect I get “An unexpected error has occured. For more information, Troubleshoot connecting computers to the server.”  I’m unable to remove the offline computers from the DX4000. The “remove a computer” dialog hangs and never finishes.

Look what I found from Microsoft Support:


When I try to connect a client computer to the server, I receive the error message, “An unexpected error has occurred. To resolve this issue, contact the person responsible for your network.”


The WSS Certificate Web Service might not be running.


Start the WSS Certificate Web Service.

To start the WSS Certificate Web Service

On the server, click  Start , click  Administrative Tools , and then click Internet Information Services (IIS) Manager.

In the navigation pane, click  WSS Certificate Web Service.

In the Actions pane, click  Start.

Also check out:

SOLVED: Western Digital DX 4000 which has Windows Storage Server 2008 R2 Essentials on it.
· Computers appear “offline” and backups fail with permissions errors.
· Cannot join a domain or joined domain permissions are missing.
· Computer monitoring errors appear in the alerts area.
· These errors occur because Windows Best Practice Analizer is installed on the server or the router/firewall has MULTICAST enabled.
· Uninstalling WBA and disabling Multicast resolves the permission issues and computer monitoring errors.
· Rebooting the client computers brings them back “on-line”.

Good find !  I knew that the BPA would cause monitoring errors, but had not heard about the multicast problems.