Always advertising, but with only one connection

Hi,

I have two NRF52840, as peripheral and central. The central is scanning and connects automatically to the peripheral.
I'm using Zephyr and NCS 2.5.1

How is it possible that I keep advertising after the connection is establish, but forbit to allow a second connection? Like act as a beacon after a connection is established.

I've tried setting CONFIG_BT_MAX_CONN=2, then the peripheral keeps advertising, but a second central can easily connect.
I've tried stopping advertising manually after the first connection is established and then tried to start advertising as non connectable, but then I get a reset and fault instruction error.

Do you have any hints for me, i appreciate it.

Thanks and Best Regards,
Phobios