On March 22, 2026, an application built using Docker failed to connect to the internal network server address. If the hostname is used, the following error message appears: If an internal IP address is used, the following error message will be displayed:

Fix Plan

To resolve the issue, we need to update the Docker configuration to allow the container to access the internal network server address using HTTPS.

Here are the steps:

• Update the docker-compose.yml file to include the https protocol in the URL.
• Add a self-signed certificate or a trusted certificate to the container.

Example docker-compose.yml update:

version: '3'
services:
  matrix:
    ...
    environment:
      - MATRIX_HOMESERVER_URL=https://synapse:8008

Alternatively, you can use the internal IP address with HTTPS:

version: '3'
services:
  matrix:
    ...
    environment:
      - MATRIX_HOMESERVER_URL=https://172.29.0.88:8008

If you are using a self-signed certificate, you may need to add the --insecure flag to the Docker run command or set the MATRIX_HOMESERVER_VERIFY_SSL environment variable to false.

Verification

To verify that the fix worked, restart the Docker container and check the logs for any errors. You can also use a tool like curl to test the connection:

curl -k https://synapse:8008

or

curl -k https://172.29.0.88:8008

If the connection is successful, you should see a response from the server.

Extra Tips

• Make sure to update the docker-compose.yml file correctly and restart the container after making changes.
• If you are using a self-signed certificate, be aware of the security implications and consider using a trusted certificate instead.
• You can also use a reverse proxy like NGINX to handle the HTTPS connection and forward requests to the internal server.