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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 this week

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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