Troubleshooting RPC unavailability issues

The 'RPC server is unavailable' error occurs when the Windows device is having a problem in communicating with other remote devices.

Common causes of RPC error:

1. The remote device is actually down / Network connection between the OpManager server and remote machine is down.
2. Device DNS or IP has changed / Device is not reachable via DNS or IP.
3. NS-lookup and reverse lookup to the device is failing.
4. Firewall is blocking the connection between OpManager Server and the remote machine.
5. The RPC and WMI Services might be down on the remote machine.

Troubleshooting steps to resolve this error:

1. Network Connectivity:
   • Note down the IP and DNS name of the remote device from its Device Snapshot page.
   • Try Ping using IP and DNS Name. If Ping failed by IP / DNS,
     • Confirm if the remote device is down and the network connection to the remote device is proper.
     • Confirm whether the device current IP and DNS name is different from IP/DNS name on device snapshot page.
   • If the IP address for the particular device has changed, you can update it from Device Snapshot page → Edit Device Details → Update the Current IP address. You can update it here and click on 'Save'.
      
   • If DNS name has changed:

     If the device is not reachable through DNS name, you can try changing the mode of polling from DNS to IP Address from Device Snapshot → Edit device details (Note that this method is applicable only for build version greater than 124089). If the build version of your OpManager installation is less than 124089, try the following steps:

     • Obtain the current DNS name. If DNS has not been resolved, then use the device's IP address instead.
     • Go to Device Snapshot page and take the DeviceMOName from the URL (the last part of the URL).
     • Use the MOname in the following DB query in OpManager:
       select * from node where name='Problematic_DeviceMOName';
     • Make sure the submitted query returns only a single row, and then proceed to update the following:
       update node set dnsname='CurrentDNSOrCurrentIP' where name='Problematic_DeviceMOName';
     • Finally, restart OpManager service to apply these settings.
2. Unable to resolve DNS or NetBIOS names:
   Check if nslookup and reverse nslookup are returning expected responses. If either of these aren't responding properly, try executing the below steps with proper consultation with your network admin.
   • Execute the below command in OpManager server and in problematic device and try nslookup again.
     ipconfig /flushdns
     Note: This command will refresh the IP Vs DNS entries.
   • Invalid entries in ETC Hosts File:
     If you're able to access the device using IP address, but not by DNS name or Host name, the issue may be due to some wrong entries in the hosts files in C:\Windows\system32\drivers\etc\hosts. Remove the wrong entries in the file and try with the proper DNS name/Host name.
3. Wbemtest Fails with RPC error:
   (Note: Before trying this method, ensure that there are no issues with your network connections.)
   We can use wbemtest to find the error message when attempting to connect to the remote system.
   • Click on Start → Run → wbemtest.
   • It opens up the Windows Management Instrument Tester. Click the Connect button.
   • In the first text box (root\default), type <\\IPAddress\root\cimv2>.
   • Provide the credentials, and click the 'Connect' button. If the connection fails, proceed with the steps below.
   If the connection is successful, but OpManager still shows RPC as unavailable, it might be due to some misconfiguration in your network. Please contact our support team for more details.
4. Firewall port blocking:
   
   • Check if there are any firewalls between the OpManager Server and the remote Windows machine.
   • If there is/are firewalls, then you will have to open up the ports in firewall for monitoring. The port is 135 (RPC).
   • For servers with Windows 2008 and above, please make sure the ports 49152 through 65535 are open in the firewall, since random ports will be chosen from them.
5. RPC and WMI Service Unavailability:
   To check whether the RPC and WMI Services are running in the remote machine:
   • In the remote machine, go to Start → Run → services.msc.
   • Check whether the services Remote Procedure Call and Windows Management Instrumentation are running. If not, start those services.

If the issue persists, please get in touch with our support team for further assistance.