Meshtastic requires the Arduino bootloader on RAK WisBlock nRF52-based boards. The process of converting the bootloader only needs to be performed once.
Starting DFU upgrade of type 2, SoftDevice size: 0, bootloader size: 39000, application size: 0
Sending DFU start packet
Timed out waiting for acknowledgement from device.
Failed to upgrade target. Error is: No data received on serial port. Not able to proceed.
```
You will need to follow the first part (through the `AT+BOOT` command) of the [Converting RAK4631-R to RAK4631](https://docs.rakwireless.com/product-categories/wisblock/rak4631-r/dfu/#converting-rak4631-r-to-rak4631) instructions.
This conversion requires the use of either a [DAPLink](https://daplink.io/) or [J-Link](https://www.segger.com/products/debug-probes/j-link/). The most reasonably priced and available is the [RAKDAP1](https://store.rakwireless.com/products/daplink-tool).