TL;DR — Quick Summary

Aspel license server communication error and connection failure: fix firewall blocking, wrong IP, stopped service, and port conflicts in Windows

When Aspel products (SAE, COI, NOI, BANCO, PROD) display a communication error while trying to connect to the license server, no user can log into the system and business operations come to a halt. The error message indicates that the program cannot establish communication with the license server, preventing the multi-user license validation needed for multiple people to work simultaneously in the system.

The Error

When opening any Aspel product configured in multi-user mode, the system shows one of these messages:

“No se puede establecer comunicación con el servidor de licencias” (Cannot establish communication with the license server)

“Error de comunicación con el servidor de licencias. Verifique que el servicio esté activo” (Communication error with the license server. Verify that the service is active)

“No se encontró el servidor de licencias en la dirección especificada” (License server not found at the specified address)

“La conexión con el servidor de licencias ha sido rechazada” (Connection to the license server has been refused)

The error appears in these scenarios:

  • When opening Aspel SAE, COI, NOI, or another product for the first time in the morning
  • After a restart of the server or the computer where the license server is installed
  • When the server IP address changes (via DHCP or network reconfiguration)
  • After a Windows update that modifies firewall rules
  • When Windows Defender or another antivirus blocks the service

Root Cause

The Aspel license server is a Windows service that listens on a specific TCP port (default 17000) and validates that the number of simultaneously connected users does not exceed what the license allows. The communication error occurs when client computers cannot reach this service:

Firewall blocking the port. Windows Firewall or Windows Defender Firewall blocks incoming connections on port 17000 by default. Each Windows update can reset firewall rules, removing previously configured exceptions. Third-party antivirus software like Norton, Kaspersky, or ESET can also block this traffic.

Incorrect IP address. If the server obtains its IP via DHCP, it may change after a restart. Aspel clients have the server’s previous IP configured and cannot locate it at the new address. This also happens when the license server is migrated to another computer without updating the client configuration.

Service stopped. The “Aspel Servidor de Licencias” service can stop for various reasons: an unexpected server shutdown, a Windows update that restarts the computer, or a startup type configuration set to “Manual” instead of “Automatic”. If the service is not running, no client can connect.

Port conflict. Another application may have taken port 17000 before the license server starts. Applications such as web servers, databases, or even other license servers can compete for the same port.

Windows Defender interference. Windows Defender real-time protection can identify the license server as suspicious activity and block it, especially after antivirus engine updates.

Step-by-Step Solution

1. Verify the service status

On the computer where the license server is installed:

  1. Press Windows + R and type services.msc
  2. Find Aspel Servidor de Licencias in the list
  3. Verify the Status is Running
  4. If stopped, right-click > Start
  5. Change the Startup type to Automatic so it starts with Windows

If the service does not appear in the list, you need to reinstall the license server from the Aspel installer.

2. Confirm the server IP address

On the server computer:

ipconfig

Note the IPv4 Address (example: 192.168.1.100). On each client computer where Aspel shows the error:

  1. Open the Aspel product
  2. If it allows access to settings without a license, go to Configuration > License Server
  3. Verify the registered IP matches the server’s current IP
  4. If the IP changed, update it and restart Aspel

To prevent future changes, assign a static IP to the server or configure a DHCP reservation on the router.

3. Configure Windows Firewall

On the server computer:

  1. Open Control Panel > Windows Defender Firewall > Advanced Settings
  2. Go to Inbound Rules > New Rule
  3. Select Port > TCP > Specific local port: 17000
  4. Select Allow the connection
  5. Apply to Domain, Private, and Public profiles
  6. Name the rule: “Aspel License Server”

Also create a rule for the executable:

  1. New Rule > Program
  2. Browse to the license server path (typically C:\Program Files (x86)\Aspel\Servidor de Licencias\)
  3. Select the server executable
  4. Allow the connection on all profiles

Repeat the port configuration on each client computer (outbound rule for port 17000).

4. Verify the port is not in conflict

On the server computer, open a command prompt as administrator:

netstat -ano | findstr 17000

If another process is using the port:

  1. Identify the conflicting process PID in the last column
  2. Run tasklist /fi "pid eq [PID]" to see which program it is
  3. Stop that program or change the license server port in its configuration

5. Configure Windows Defender exceptions

  1. Open Windows Security > Virus & threat protection > Settings
  2. Go to Exclusions > Add an exclusion
  3. Add the license server folder: C:\Program Files (x86)\Aspel\Servidor de Licencias\
  4. Also add port 17000 as an exclusion if your antivirus supports it

6. Test the connection from the client

From the client computer, open a command prompt:

telnet 192.168.1.100 17000

If the screen goes black, the connection was successful. If it shows “Could not open connection”, the problem is with the network, firewall, or server service.

If telnet is not available, use:

Test-NetConnection -ComputerName 192.168.1.100 -Port 17000

Alternative Solution

If the license server continues not responding:

  1. Uninstall and reinstall the license server from the original Aspel installer
  2. Change the port in the license server configuration to a different one (example: 17001) and update the configuration on all clients
  3. Verify the subnet: make sure the server and clients are on the same subnet (for example, 192.168.1.x with mask 255.255.255.0). If they are on different subnets, you need to configure routing between them
  4. Temporarily disable all antivirus and firewall software to confirm they are the cause. If Aspel connects without them, reconfigure the exceptions

Prevention

  • Assign a static IP to the server computer or configure a DHCP reservation on the router so the IP does not change
  • Set the service startup type to Automatic (Delayed Start) so it starts after the network is available
  • Document firewall rules and verify they remain active after each Windows update
  • Add antivirus exclusions before installing the license server to prevent blocks
  • Monitor the service with a scheduled script that checks if it is running and automatically restarts it if stopped
  • “No se logró registrar la serie en el servidor de licencias” (Failed to register the serial): The product serial is not registered correctly. Open the license server manager and register the serial manually.
  • “Se excedió el número máximo de usuarios” (Maximum number of users exceeded): All licenses are in use. Close inactive sessions or acquire additional licenses.
  • “El servidor de licencias no se instala correctamente” (License server does not install correctly): Run the installer as administrator and verify that .NET Framework 3.5 is enabled in Windows features.

Summary

  • The Aspel license server communication error prevents SAE, COI, NOI, and other products from validating the multi-user license
  • Verify the Aspel Servidor de Licencias service is running and configured for automatic startup
  • Confirm the server IP address is correct in each client’s configuration
  • Configure Windows Firewall exceptions for TCP port 17000 and the server executable
  • Assign a static IP to the server and document firewall rules to prevent recurring issues