watchOS 6 TCP Connection - The operation couldn’t be completed. (kCFErrorDomainCFNetwork error -72000)

I'm developing a watchOS 6 standalone app with Xcode and Objective-C. This app should connect to a TCP server. If I run the app on the simulator it works, if I run it on my physical Apple Watch Series 4 I get this error: The operation couldn’t be completed. (kCFErrorDomainCFNetwork error -72000).

Here is the code:

InterfaceController.h

#import <WatchKit/WatchKit.h>
#import <Foundation/Foundation.h>

@interface InterfaceController : WKInterfaceController <NSStreamDelegate>
{
  CFReadStreamRef readStream;
  CFWriteStreamRef writeStream;

  NSInputStream *inputStream;
  NSOutputStream *outputStream;

  NSMutableArray *messages;
}


@property (weak, nonatomic) IBOutlet WKInterfaceLabel *connectedLabel;
@property (weak, nonatomic) IBOutlet WKInterfaceLabel *dataReceivedLabel;



@end

InterfaceController.m

#import "InterfaceController.h"


@interface InterfaceController () {
  NSString* dataToSend;

  // Server Info
  NSString* ipAddress;
  NSString* port;
}

@end


@implementation InterfaceController

@synthesize connectedLabel;
@synthesize dataReceivedLabel;

- (void)awakeWithContext:(id)context {
  [super awakeWithContext:context];

  ipAddress = @"192.168.0.68";
  port = @"12345";

  dataToSend = @"Hello TCP!";
  [connectedLabel setText:@"Disconnected"];

}

- (IBAction)sendMessage {
  NSString *response = [NSString stringWithFormat:@"msg:%@", dataToSend];
  NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]];
  [outputStream write:[data bytes] maxLength:[data length]];
}

- (void) messageReceived:(NSString *)message {

  [messages addObject:message];

  [dataReceivedLabel setText:message];
  NSLog(@"%@", message);
}

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {

  NSLog(@"stream event %lu", (unsigned long)streamEvent);

  switch (streamEvent) {

  case NSStreamEventOpenCompleted:
  NSLog(@"Stream opened");
  connectedLabel.text = @"Connected";
  break;
  case NSStreamEventHasBytesAvailable:

  if (theStream == inputStream)
  {
  uint8_t buffer[1024];
  NSInteger len;

  while ([inputStream hasBytesAvailable])
  {
  len = [inputStream read:buffer maxLength:sizeof(buffer)];
  if (len > 0)
  {
  NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

  if (nil != output)
  {
  NSLog(@"server said: %@", output);
  [self messageReceived:output];
  }
  }
  }
  }
  break;

  case NSStreamEventHasSpaceAvailable:
  NSLog(@"Stream has space available now");
  break;

  case NSStreamEventErrorOccurred:
  NSLog(@"%@",[theStream streamError].localizedDescription);
  break;

  case NSStreamEventEndEncountered:

  [theStream close];
  [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
  connectedLabel.text = @"Disconnected";
  NSLog(@"close stream");
  break;
  default:
  NSLog(@"Unknown event");
  }
}

- (IBAction)connectToServer {
  NSLog(@"Setting up connection to %@ : %i", ipAddress, [port intValue]);

  CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef) ipAddress, [port intValue], &readStream, &writeStream);

  messages = [[NSMutableArray alloc] init];

  [self open];
}

- (IBAction)disconnect {
  [self close];
}

- (void)open {

  NSLog(@"Opening streams.");

  outputStream = (__bridge NSOutputStream *)writeStream;
  inputStream = (__bridge NSInputStream *)readStream;

  [outputStream setDelegate:self];
  [inputStream setDelegate:self];

  [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
  [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

  [outputStream open];
  [inputStream open];

  [connectedLabel setText:@"Connected"];
}


- (void)close {
  NSLog(@"Closing streams.");
  [inputStream close];
  [outputStream close];
  [inputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
  [outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
  [inputStream setDelegate:nil];
  [outputStream setDelegate:nil];
  inputStream = nil;
  outputStream = nil;

  [connectedLabel setText:@"Disconnected"];
}


@end