How to change data rate of DWM3000

I’m using the DW3XXX_API_rev9p3 AP in combination with the following hardware: nRF52840-DK and DWM3000EVB (DWS3000).
The basis of my development are the examples “ds_twr_initiator” and “ds_twr_responder”. So I’m able to compile and execute these examples.

After that I tried to change the data rate from 6,8M to 850k.

/* Default communication configuration. We use default non-STS DW mode. */
static dwt_config_t config = {
    5,               /* Channel number. */
    DWT_PLEN_128,    /* Preamble length. Used in TX only. */
    DWT_PAC8,        /* Preamble acquisition chunk size. Used in RX only. */
    9,               /* TX preamble code. Used in TX only. */
    9,               /* RX preamble code. Used in RX only. */
    1,               /* 0 to use standard 8 symbol SFD, 1 to use non-standard 8 symbol, 2 for non-standard 16 symbol SFD and 3 for 4z 8 symbol SDF type */
    DWT_BR_850K,     /* Data rate. */
    //daDWT_BR_6M8,    /* Data rate. */
    DWT_PHRMODE_STD, /* PHY header mode. */ 
    DWT_PHRRATE_STD, /* PHY header rate. */
    (129 + 8 - 8),   /* SFD timeout (preamble length + 1 + SFD length - PAC size). Used in RX only. */
    DWT_STS_MODE_OFF, /* STS disabled */
    DWT_STS_LEN_64,/* STS length see allowed values in Enum dwt_sts_lengths_e */
    DWT_PDOA_M0      /* PDOA mode off */

After this changes (same data rate on both projects) I was able to compile the project and upload it, but I don’t get a range between the two boards. Are there some additional changes necessary to run this project on DWT_BR_850K?

You may need to increase some timeout values, lower data rates mean the packets take longer to transmit so all of the times will be larger.