Arduino unr r4 mini doesn't reconnect to serial port after manual reset

[mirjahaal]

I'm testing the Uno R4 Minima and tried a simple sketch:

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);

  //make sure the computer is actually waiting for the arduino
  bool synced == false;

  while(not synced) {

    //wait for serial input
    while(Serial.available() == 0) {
      Serial.println("sync");
      delay(1000);
    }//while(Serial.available() == 0)

    //get serial input
    String recieved = Serial.readStringUntil('\n');

    //if synced, break outer loop
    if(recieved == "synced"){
      Serial.println("synced");
      synced = true;
    }
    
    else{
      Serial.println("not synced");
    }

  }//while(not synced)
}// void setup

If I hit the reset button, the serial port seams to close as I can't reopen the serial monitor and have to manually reselect the port in the "tools"-menu.
I don't understand what's going on and would like to know how to avoid this.
With the old Uno R3 it worked perfectly fine.

[mirjahaal]

I found a solution thanks to @KurtE in this post.
The line
while (!Serial && (millis() < 5000));
let's the R4 reconnect correctly after reset. For explanation, see the original post.

[gilshultz]

That may not work with all computers. When you reset the USB port disconnects then when it reconnects your computer re-enumerates the USB port. Generally but not always it will come back the same. On my machine it changes to generally the next higher port.