Hotfix available for the Remote Desktop Services’ ‘Maximum Connections Reached’ error in UAG

Your computer can't connect to the remote computer because the Remote Desktop Gateway server reached its maximum allowed connections. Try reconnecting later or contact your network administrator for assistance

Background: Since the release of UAG, there have been customers reporting a problem where the maximum number of connections was reached when accessing the Remote Desktop services from the UAG portal. If you viewed the “Windows Terminal Services - Gateway” event logs you would see events complaining about the maximum number of connections. For example, Event ID 203 reads:

Event ID: 203
Source: Microsoft-Windows-TerminalServices-Gateway

Message: The number of simultaneous connections to the RD Gateway server has reached the maximum number that was configured by the administrator. The server is therefore not accepting any new connections. (Message Continues…)

Cause of the issue: UAG relies on Windows 2008 R2 Remote Desktop Gateway services for publishing RDS. The maximum connection issue occurs because the sessions of the previously connected users weren’t properly getting terminated and the maximum connection limit was reached due to the buildup. So, when the number of concurrent connections to the RD Gateway server reaches the maximum, 250 in the Windows 2008 R2 Standard edition, all new requests were being denied and presented with the error shown above. Interestingly, when looking in the Remote Desktop Gateway Management console, you may see the number of active connections well below the maximum concurrent limit of 250. What’s going on with the non-terminated connections?

We have gone through extensive testing and troubleshooting in the past to overcome this error to ensure smooth RDS publishing in UAG running on Windows 2008 R2 Standard Edition, but the solutions failed to remove the un-terminated sessions from the RDS.

Changing registry settings to make it identical with enterprise edition and restarting the RDG service.

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\TerminalServerGateway\Config\Core "MaxConnections"=dword:ffffffff

Changing registry settings to:

Under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Terminal Server Gateway, create key Transports, under Transports create key Rpc and then under Rpc create Dwordvalue : DisconnectSweepPeriod = 1

The only thing worked so far was to restart the Remote Desktop Gateway service.  By restarting the gateway service, all stale connections are cleared out. But, the flip side of this solution is all of the currently connected RDG connections will be dropped. This is not acceptable in live production environment. Until February 2012 there was no solid solution available for UAG installed on Windows 2008 R2 Standard, but luckily Microsoft has now released a hotfix to address this issue. It can be downloaded from: http://support.microsoft.com/kb/2649422.

Cheers
nAppliance Support Team