Dual-band Receiver (DBR4) build fails when both 2.4GHz and 868MHz regulatory domains are selected

[datadorf]

I’m using the RadioMaster DBR4-TD Dual Band Receiver, which supports both 2.4 GHz and 868/900 MHz bands simultaneously. When trying to build ExpressLRS for this receiver (target: Unified_ESP32_LR1121_RX_via_UART), the build fails if both regulatory domains (2.4 GHz + 868 MHz) are selected in the configurator.

Here’s the error message I get:

!!! Regulatory_Domain 2400 not compatible with RADIO_SX127X/RADIO_LR1121 !!!

This is confusing because the hardware clearly supports both bands. It seems like the build system expects only one domain at a time depending on the target radio chipset.

Suggested improvements:
1. Detect this and show a clearer message in the Configurator.
2. Allow a dual-regulatory build for dual-band receivers like DBR4.
3. Document clearly which bands are supported per chip/target during build.

Cheers

[Jannik-23]

Hello,
I Have the same Issue. Is there a way to prevent this from happening ?

I want to use the Nomad with the XR4 and the DBR4

Greetings

[944evan959]

Same issue for the Radiomaster TX15