Hi,
1. Make sure that RPC traffic is open on the firewall between the SCE server and the client. For example, if you have a ISA firewall, make sure the RPC filter is disabled.
Just for your reference, the following are port requirements of the remote procedure call (RPC):
RPC run-time on one server always connects to the remote server's RPC Endpoint Mapper at a well-known port (port 135). The RPC Endpoint Mapper then assigns dynamically assigned ports between 1024-65535 (by default) for replication.
This is why by default port 135 TCP/UDP and ports 1024-65535 TCP must be open for RPC to work.
2. Verify that Enable RSS, Enable TCP and Enable TCP Chimney were set to 0 in registry HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters.
Here is a KB article for your reference:
The Microsoft Windows Server 2003 Scalable Networking Pack release
http://support.microsoft.com/kb/912222
3. Verify RPCSS is enabled. Please refer to:
Error messages are logged in the SQL Server error log when you use SQL Server 2000 on a computer that is running Windows 2000 Server Service Pack 4 or Windows Server 2003
http://support.microsoft.com/kb/917405
4. Please ensure the client is a member of "SCE Managed Computers" group in AD users.
5. Please make sure two GPO which are created during installation set to enforce.
6. Enable "Windows Firewall: Allow inbound remote administration exception". Refer to the following article:
7. If you do have a program exception, but wish to still prevent allow local program exceptions, then you can add a further remote program exception to your group policy as follows:
%SystemRoot%\422C3AB1-32E0-4411-BF66-A84FEEFCC8E2\MOMAgentInstaller.exe:SCE server IP address:enabled:MOMAgentInstaller
How to Change Windows Firewall Exceptions for System Center Essentials
http://technet.microsoft.com/en-us/library/bb437377.aspx
8. Check whether you can resolve the client’s name correctly.
9. Reboot the client, and then try to install then agent again.
