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DNS and Network Requests for Firewall Whitelists

If there is a corporate firewall or even a private DNS filter on your network, like Pi-Hole, learn what domains should be whitelisted for TRMNL devices to retrieve new screens.

Mario avatar
Written by Mario
Updated over 3 weeks ago

This information only applies to using usetrmnl.com as your device's server (where you organize plugins and playlists). If you are using a BYOS (Bring Your Own Server) solution, this is not applicable unless proxying (server-specific feature).

There are only three domains that your TRMNL device uses to download its next screen:

  • https://trmnl.app - Receiving information about the next screen

  • https://time.google.com - Accurate time keeping

  • https://trmnl.s3.us-east-2.amazonaws.com - Downloading the screen itself (PNG file)

Note that the Alias and Redirect plugins are special and designed so you can make requests to unique sources for image screens.

If a TRMNL device can connect and retrieve screens via one network or hotspot but not another, and you are sure the WiFi connection is working properly, this can be a possible cause of problems in restrictive environments.

If you are on a corporate network, it may require whitelisting to access particular domains, or verifying that traffic to these domains is not blacklisted.

Pi-Hole Query Log

If you use Pi-Hole as a DNS server in your home network, you can check your query log to ensure all requests are being allowed through:

If any of these requests are blocked, your TRMNL device will not be able to retrieve the next screen to display.

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