Beetle ESP32-C6 Serial Monitor not working

I am using a Beetle ESP32-C6 and am trying to get some simple serial output using Arduino 1.8.19

To get the board to show I used the suggestion of Laurent.VOLPON here https://www.dfrobot.com/forum/topic/332564

I then used the following settings:

Board: “DFRobot Beetle ESP32-C6” (also tried “DFRobot FireBeetle 2 ESP32-C6”)

USB CDC On Boot: “Disabled” (more on that later)

Other parameters identical to https://wiki.dfrobot.com/SKU_DFR1117_Beetle_ESP32_C6

With these parameters I can write blink without a problem, the board stays connected after uploading the sketch and the code runs directly.

I expanded blink to 

int led = 15;
void setup() {
 pinMode(led,OUTPUT);
 Serial.begin(115200);
 while(!Serial) {;}
}

void loop() {
 digitalWrite(led,HIGH);
 delay(500);
 digitalWrite(led,LOW);
 delay(500);
 Serial.println("hello");
}

The serial monitor in Arduino, as well as in PuTTY  don't show anything. In PuTTY I can setup a serial connection but it stays empty.

When I changed USB CDC On Boot to Enabled, as it should be according to the manual (see link above), I started having connection problems. Only after combinations of BOOT + RST on the Beetle the board connects to the PC and uploading sketches works, however the sketch does not run after this (no blinking).

Pressing RST makes the code run, but then the USB disconnects.

I re-installed the drivers (the usbser.sys driver is being used) and tried out a bunch of different settings in Arduino and PuTTY to try to get this to work without success.