PChucks Network: Server Availability Affected By Maximum Simultaneous Connections

With Windows 2000, XP, and Vista, you are subject to a limitation on the (KB314882): number of simultaneous connections that a server can provide. If you have more than 5 connections to a server running a Home edition, or 10 connections to a server running a Business or Professional edition, you may observe various symptoms:

The error "No more connections can be made to this remote computer at this time because there are already as many connections as the computer can accept."
The error "Server is not accessible...".
As connections time out from disuse, they will become disconnected. Attempts to reconnect will either result in the above errors, or will force the disconnection of another, less active computer.

The good news is, you can't use up all of your connections on any server from any one client, with multiple sessions on that server. Generally, one account on one client with multiple sessions = 1 connection. A session started by a user, and another session started by the system account, from one client, will count as 2 connections, though. And multiple protocols, for instance NetBEUI and TCP/IP, if both are used for file sharing, will count as 2 connections by a single client.

Check the connections in use on your server, using one of two tools - the GUI Shared Folders wizard, or the command window Net commands.

As a client becomes inactive on a server, its connection will timeout, and become available to another client. The default period for inactivity to trigger a disconnection is 15 minutes.

If you need many more client connections than the server can provide, you can lower the timeout period, by tuning the server. Microsoft (KB314882): Inbound connections limit in Windows XP tells us how to change the timeout period to 10 minutes, for instance. Into a command window, enter:

net config server /autodisconnect:10

But beware. Changing the timeout period, by using "net config", may affect server functionality, permanently.

The Windows Server service is self-tuning; normally the server configuration parameters are autoconfigured (calculated and set) each time you start Windows XP. If you run net config server in conjunction with the /autodisconnect, /servcomment or /hidden options, the current values for the automatically tuned parameters are displayed and written to the registry. After these parameters are written to the registry, you cannot tune the Server service by using the Networks tool in Control Panel. If you change any of the Server service settings, Windows XP can no longer automatically tune the Server service for your new configuration. To avoid losing the Server service's automatic self-tuning capability, make the change through Registry Editor instead from a command line or Control Panel Network.

You may want to use the Local Security Policy Editor (for XP Pro only) instead. Under Security Options, you should find "Microsoft network server: Amount of idle time required before suspending session". Or, you may prefer to edit the registry directly, and change Registry Value [HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\autodisconnect]. Change either the LSP entry (for XP Pro), or the registry value, to an appropriate setting.

Now, knowing that there is a limitation is slightly easier to deal with when you have some way of monitoring use, so you can prevent exceeding the limitation, or at least know when you have exceeded it. See Know Who's Accessing The Server, for discussion about the GUI Computer Management - Shared Folders wizard, and for the Command Windows utility Net command.

You may find additional information of interest in the Microsoft articles

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