Change Channel Selection Algorithm (CSA) from default 2 to 1 in nRF52840DK

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Hi,
my today's task is to replace a Pheriperal device in a customer BLE system (Target: nRF52820). Finally I've managed to setup ADV_IND and SCAN_RSP data packets the same. But unfortunately the device (nRF52840DK + nRF SDK 2.1.3) does not connect to the existing Central but works fine with iPhone and Android devices.
Thanks to BLE Sniffer I've found some differences inside BLE headers (see images attached - original (customer device) on right sight, nRF52840DK on left side).
The switches inside proj.conf (see devzone.nordicsemi.com/.../channel-selection-algorithms-in-nrf52840dk)

CONFIG_BT_CTLR_ADV_EXT=n
CONFIG_BT_CTLR_CHAN_SEL_2=n

do not work.

• How to change CSA from 2 to 1?
• How to change TxAdd from "Random" to "Public"

Customer needs to achieve connectivity to quite a lot existing devices.

Thanks in advance!

[[email protected]]

After changing both the devices now connect, but after a timout (some seconds) they disconnect unfortunately. But this seems to be another problem I have to investigate next.