MKNetworkKit file upload not working on iOS

I use MKNetworkKit perfectly for all my server requests. However, when trying to load an image file, it fails with this error:

Domain Error = NSURLErrorDomain Code = -1005 "The network connection was lost." UserInfo = 0x1010cb20 {NSErrorFailingURLStringKey = https://s3.amazonaws.com/net.myapp.upload, NSErrorFailingURLKey = https://s3.amazonaws.com/net.myapp.upload, NSLocalizedDescription = The network connection was lost., NSUnderlying = 0x1010ca60 "The network connection was lost.}

Sometimes the error code is 405. I have all the amazon credentials required to boot, and running cURL in a terminal with the same outgoing data as the application gives a correct return. The method I'm using for this request is here:

 - (MKNetworkOperation*)uploadMediaFromFile:(NSString*)file urlCommand:(NSString*)url    
 postField:(NSString*)field authDict:(NSMutableDictionary*)authDict onCompletion:(   
 MediaUploadBlock)completionBlock onError:(MKNKErrorBlock)errorBlock  {

    MKNetworkOperation *op = [self operationWithURLString:url params:authDict                           
     httpMethod:@"POST"];

    [op addFile:file forKey:field];

    // setFreezable uploads your images after connection is restored!
    [op setFreezable:YES];

    [op onCompletion:^(MKNetworkOperation* completedOperation) {
        NSLog(@"%@",[completedOperation responseString]);
        NSDictionary *jsonString = [completedOperation responseJSON];
        NSLog(@"%@",jsonString);
        completionBlock(jsonString);
    }
     onError:^(NSError* error) {
         errorBlock(error);
     }];

    [self enqueueOperation:op forceReload:YES];

    return op;
 }

      

        
        
        
      

    

This is a fairly simple request that works from the terminal and works in the browser using the same parameters as here. I can't figure out why this doesn't work. Any help is appreciated.