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Finding your TRMNL Mac Address

For debugging and customer support.

Ryan avatar
Written by Ryan
Updated this week

Every TRMNL has 2 immutable characteristics -- a Mac Address, and a Serial.

Mac Addresses are generated by our manufacturer, and Serial values are printed directly on the PCB (circuit board).

In some cases, TRMNL may need to know one of these values to help debug a connection issue. But instead of disassembling your device, we suggest looking up your Mac Address instead.

Option A - WiFi Router settings

Pending your local network setup, you may have access to a wireless router settings interface or mesh network mobile app. This app will present a list of devices like your phone, television, computers, and so on.

If you have access to such an interface, look for a device whose name starts with "ESP_", followed by a few random characters. Select that device and you should see a "MAC" value such as AB:4D:CA:FF:Q1.

Option B - WiFi Portal Footer

Put your TRMNL in "pairing mode" by turning it on, waiting for it to boot, then holding the button on the back (next to the on/off switch) for 5-6 seconds.

Let go of the button, then wait for TRMNL to show a WiFi setup screen like this:
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Connect to the WiFi network named "TRMNL," and you should see a screen like this:

Using Firmware 1.5.11 (released July 11, 2025)

If you're on the latest firmware (devices update automatically), the bottom of your WiFi portal will include the MAC by default:

Using Firmware 1.5.10 or lower

To expose your MACc, input your WiFi network name (SSID) + password and tap Connect. For 1-2 seconds, your MAC will appear at the bottom like so:

This screen disappears quickly, so it's easiest if you take a screenshot when you see the grey bar. You can do this with your phone's screen grab shortcut or on your computer, if you access this WiFi portal from a web browser.

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