MDNS query don't work?

gistfile1.txt

WiFi.setHostname("espressif");
MDNS.begin("espressif");
   delay(2000);
MDNS.addService("_osc","_udp",4500);
MDNS.addServiceTxt("_osc","_udp","does","it");

   delay(2000);

    
int n = MDNS.queryService("osc", "udp"); // Send out query for esp tcp services
if (n == 0) {
  dbgstream->println("\tno services found");
} else {
  dbgstream->printf(" \t%d services found\n", n);       
  for (int i = 0; i < n; ++i) {
      // Print details for each service found
      dbgstream->printf("\t%d: %s (%s:%d)\n",
          (i+1), MDNS.hostname(i).c_str(), MDNS.IP(i).toString().c_str(), MDNS.port(i));
  }
}