You’re probably right here because you’re trying to set up a multi-box biztalk installation (1 biztalk machine and 1 database server wherein SSO is installed) and encountered a nasty RPC Server unavailable. First thing to check is whether the MSDTC settings is correctly setup, check the guide from Sandro here .

After that is done and still there is an error it’s caused by the Windows Firewall settings. To solve this issue, follow the steps below:

1. In the  command prompt type: Regedt32.exe

With Registry Editor, you can modify the following parameters for RPC. The RPC Port key values discussed below are all located in the following key in the registry:

HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\ Key Data Type

Ports REG_MULTI_SZ

Specifies a set of IP port ranges consisting of either all the ports available from the Internet or all the ports not available from the Internet. Each string represents a single port or an inclusive set of ports. For example, a single port may be represented by 5984, and a set of ports may be represented by 5000-5100. If any entries are outside the range of 0 to 65535, or if any string cannot be interpreted, the RPC runtime treats the entire configuration as invalid.

PortsInternetAvailable REG_SZ Y or N (not case-sensitive)

If Y, the ports listed in the Ports key are all the Internet-available ports on that computer. If N, the ports listed in the Ports key are all those ports that are not Internet-available.

UseInternetPorts REG_SZ ) Y or N (not case-sensitive

Specifies the system default policy.

If Y, the processes using the default will be assigned ports from the set of Internet-available ports, as defined previously.

If N, the processes using the default will be assigned ports from the set of intranet-only ports.

Example:

1. Add the Internet key under:

HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc

1. Under the Internet key, add the values “Ports” (MULTI_SZ), “PortsInternetAvailable” (REG_SZ), and “UseInternetPorts” (REG_SZ).In this example ports 5000 through 5100 inclusive have been arbitrarily selected to help illustrate how the new registry key can be configured. For example, the new registry key appears as follows:

Ports: REG_MULTI_SZ: 5000-5100
PortsInternetAvailable: REG_SZ: Y
UseInternetPorts: REG_SZ: Y

1. Restart the server. All applications that use RPC dynamic port allocation use ports 5000 through 5100, inclusive. In most environments, a minimum of 100 ports should be opened, because several system services rely on these RPC ports to communicate with each other.

You should open up a range of ports above port 5000. Port numbers below 5000 may already be in use by other applications and could cause conflicts with your DCOM application(s). Furthermore, previous experience shows that a minimum of 100 ports should be opened, because several system services rely on these RPC ports to communicate with each other.

Final Step is to add a new Firewall Rule that will allow tcp connections with port range you’ve set in the registry settings.