mDNS discovery works on iOS simulator but not on real device (SocketException errno = 65)

[superwebarmy]

I’m using Flutter’s multicast_dns package to discover Android TVs on the local network using mDNS. The code works perfectly on the iOS simulator, but fails on a real iPhone with the following error:

[ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: SocketException: Send failed (OS Error: No route to host, errno = 65), address = 0.0.0.0, port = 5353
#0      _NativeSocket.send (dart:io-patch/socket_patch.dart:1521:34)
#1      _RawDatagramSocket.send (dart:io-patch/socket_patch.dart:3078:15)
#2      MDnsClient.lookup (package:multicast_dns/multicast_dns.dart:227:22)

Future<void> search() async {
  const String name = '_androidtvremote2._tcp';
  final MDnsClient client = MDnsClient();

  try {
    await client.start();

    await for (final PtrResourceRecord ptr in client
        .lookup<PtrResourceRecord>(ResourceRecordQuery.serverPointer(name))) {
      final fullName = ptr.domainName;
      final friendlyName = fullName.split('.')[0];

      await for (final SrvResourceRecord srv in client
          .lookup<SrvResourceRecord>(
            ResourceRecordQuery.service(ptr.domainName),
          )) {
        final host = srv.target;
        final port = srv.port;

        await for (final IPAddressResourceRecord addr in client
            .lookup<IPAddressResourceRecord>(
              ResourceRecordQuery.addressIPv4(host),
            )) {
          final ip = addr.address.address;
          print('Found $friendlyName at $ip:$port');
        }
      }
    }

    client.stop();
  } catch (error) {
    print(error);
  }
}

I’ve already done the following:

• Added NSLocalNetworkUsageDescription in Info.plist.

• Added NSBonjourServices with _androidtvremote2._tcp.

• Local network permission is ON in iOS Settings.

• Works fine on iOS simulator and Android devices.

• Both iPhone and Android TV are on the same Wi-Fi.

Despite all that, it always throws SocketException (OS Error: No route to host, errno = 65) on a real iPhone.

[huycozy]

Which version of multicast_dns package you are using?

Could you provide a completed and minimal reproducible code sample that doesn’t include 3rd party plugins or complex production code? Also, please provide the output of flutter doctor -v as well. Thank you!

This could be similar to dart-lang/sdk#45824 (see deduplicated issue: #138006)