Two possibilities:
1. Use RPC over HTTP (best and easiest solution)
2. Limit the RPC Ports available and open these ports on the Astaro
You have to create these registry keys on the Exchange and reboot it:
Code:
HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\ (Key)
HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\Ports ==> 40100-41099 (REG_MULTI_SZ)
HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\PortsInternetAvailable ==> Y (REG_SZ)
HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet\UseInternetPorts ==> Y (REG_SZ)