Why is MongoDB still connecting to 127.0.0.1 despite setting a custom host?

Based on the documentation, this behavior typically happens when the connection parameters in the credentials aren’t being applied as expected. Here are a few points to check:

1. Verify Your Base URL:
   Make sure you’ve updated the base URL in the Ollama credentials. On systems with IPv6 enabled, using the alias “localhost” can resolve to ::1 (or sometimes to 127.0.0.1 if the application is forcing IPv4). Since the documentation advises that if you encounter connection issues, you should change your base URL to the IPv4-specific address (e.g., http://127.0.0.1:11434), double-check that your intended host isn’t being overwritten or ignored.

2. Docker Networking Considerations:
   If you’re running n8n or Ollama in Docker, the meaning of “localhost” can change. For instance:

   • If only n8n is containerized, you might need to use host.docker.internal instead of 127.0.0.1.
   • If both are in containers, using Docker networking (e.g., by setting the Ollama container name as host) is required.

   Verify that your Docker run command (or your docker-compose configuration) correctly maps the network settings so that the credentials’ host is used.

3. Credentials and Caching:
   Ensure that the saved credentials reflect your changes. Sometimes, if you update the host in the environment or configuration file, the saved credentials might still carry a default value (127.0.0.1) if not updated. Double-check the credentials configured in n8n to ensure the new host is stored.

4. Sub-node Behavior:
   If you’re using an Ollama sub-node, keep in mind that sub-nodes resolve expressions using only the first input item. If you’re dynamically setting the host via an expression, the parameter might not process as expected. In that case, the static base URL specified in your credentials will be used.

Review these points and ensure that your configuration matches the guidelines for your specific environment. Once the credentials are correctly updated and your networking settings (especially in Docker) are correctly configured, n8n should use the provided host instead of falling back to 127.0.0.1.