How to Manage the Remote Desktop Gateway Service in SBS 2011 Standard , SBS 2011 Essentials and Windows Server 2012 Essentials.
dism /online /Enable-Feature:Gateway-UI
This command must be run from an administrative level command prompt.
We do not recommend you use Server Manager to install the Remote Desktop Gateway role. The role is already installed and configured properly for use by the SBS components. If you manually install the RD Gateway role using Server Manager, the setup process will automatically launch the configuration wizard and it may be possible to misconfigure the service and break the Remote Web Access. If you have installed the RD Gateway Manager by either the DISM command or by using Server Manager, you can run the following command to remove the RD Gateway Manager.
dism /online /disable-feature:Gateway-UI
NOTE: Typically you should not need to install the Gateway-UI feature. If you have made changes to the web site regarding certificates try the following from an administrator cmd prompt first, and then attempt to connect via RWA to a client computer.
The certificate in IIS is different from the one RD Gateway service is running with. You must restart the RD Gateway service for the new certificate to take effect and doing this will disconnect all active connections. To restart the service now, click Yes. To restart the service manually later, click No.
You should click No to the warning message.
Once the RD Gateway Manager console completely loads, you may also see the following error message:
A server certificate is not yet installed or selected.
You can safely ignore this error message as well.
The warnings and errors occur because the RD Gateway service is installed and configured by SBS setup and not by the RD Gateway setup wizard. The configuration errors and warnings can be safely ignored. The RD Gateway is properly configured for use with the Remote Web Access site by Small Business Server setup.