In this article:  

• Issue description

• Prerequisites

• Possible causes

• Resolution

• Related topics and articles

• How to reach support

 Issue description   

You may see the following message in ADAudit Plus:

No communication available from agent to server.
Last event read time: {recent event time}

This indicates that the agent has not communicated with the ADAudit Plus server for the past several hours. This typically points to connectivity or firewall-related issues.

 Possible causes   

• A firewall is blocking communication between the agent and server.

• Incorrect protocol or port configuration in the agent.

• DNS resolution failure or hostname/IP mismatch.

• The ADAudit Plus server is down or unreachable.

• TLS/SSL mismatch (e.g., HTTPS enforced without proper certificates).

 Prerequisites   

• Ensure the ADAudit Plus agent is installed and running on the monitored computer.

• The ADAudit Plus server should be up and reachable over the network.

• Communication protocol (HTTP or HTTPS) and port must be known and consistent between agent and server.

• The agent synchronizes server configurations by HTTPS communication. If HTTPS fails then the server attempts to sync all configurations with agent via RPC.

 Resolution   

 1. Verify web console access from agent machine   

From the agent machine, open a browser and attempt to access the ADAudit Plus server using the format:

https://<ADAuditServer>:<Port> (Default port is 8555 for HTTPS)

• Example: https://adaudit-server:8555

• If the page loads, the server is reachable.

• If it fails, proceed to firewall and port testing.

 2. Validate port accessibility with PowerShell   

Run the following command on the agent machine to verify connectivity to the ADAudit Plus server:

Test-NetConnection -ComputerName adaudit-server -Port 8555

Replace adaudit-server with the actual hostname or IP of the ADAudit Plus server.

Expected output should show the following:

TcpTestSucceeded : True

If the port is closed, please open the required port.

 3. Confirm firewall rules and required ports   

From the ADAudit Plus server to the monitored computers  

Ensure the following ports are open and allowed through any firewalls between the ADAudit Plus server and monitored computers:

• TCP 445 

• TCP 135 

• TCP 49152-65535  

Test access using PowerShell from the ADAudit Plus server:

Test-NetConnection -ComputerName <WorkstationName> -Port 445
Test-NetConnection -ComputerName <WorkstationName> -Port 135
Test-NetConnection -ComputerName <WorkstationName> -Port 49152

Repeat for multiple random ports in the dynamic range to confirm accessibility.

 4. Verify Server to Agent Communication 

When there is a hostname or IP address mismatch, the agent may stop communicating with the ADAudit Plus server. ADAudit Plus attempts to automatically sync server configuration with the agent if the agent has been inactive for more than two hours this check occurs every 30 minutes.

The agent first tries to synchronize configuration using HTTPS. If HTTPS communication fails, the server falls back to RPC-based synchronization. For this process to work, the following ports must be open:

If you want to perform an immediate sync instead of waiting for the next automatic attempt, follow these steps:

1. Log in to the ADAudit Plus web console.

2. Locate the Server.

3. Click Manage next to the required server.

4. Select Sync All.

This will manually update the agent’s configuration, including port, protocol, server name, IP address, and DNS information.

 Related topics and articles   

• Ports that need to be open

 When and how to reach support   

If connectivity issues persist after confirming ports and firewall rules:

1. Email the logs along with a brief issue summary to support@adauditplus.com. The support team will assist with advanced troubleshooting and resolution.