Uploading of file to server side does not trigger any errors when i disconnect my device from wifi

I am using the following code to upload a file on my server. The file starts uploading but then i disconnect my iphone device from my wifi. I do not see any errors returning...the connection keep staying alive. I waited for more than 10 minutes! completionHandler: does not trigger. I even tried setting the timeoutinterval in NSMutableURLRequest *request and AFURLSessionManager *manager to 10 seconds but no luck. Even tried reachability class inside the upload procedure but no luck. What am i missing?

    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:ccId];
        AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
       
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:preSignedURL];
        request.HTTPMethod = @"PUT";
        [request setValue:@"video/mp4" forHTTPHeaderField:@"Content-Type"];
        
        NSString* filePath = [self getFilePathForFileName:@"video.mp4" video:videoURL];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        if (![fileManager fileExistsAtPath:filePath]){
            return;
        }
    
        NSURLSessionUploadTask *uploadTask = [manager uploadTaskWithRequest:request fromFile:[[NSURL alloc] initFileURLWithPath:filePath] progress:^(NSProgress * _Nonnull uploadProgress) {
    
    NSLog(@"Upload in progress...");
    }
     completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
                NSFileManager *fileManager = [NSFileManager new];
                [fileManager removeItemAtPath:filePath error:NULL];
                if (error) {
                    NSLog(@"Error occured on video upload test: %@ for %@", error,ccId);
                    completion(nil);
                }
                else{
                    NSLog(@"%@ %@", response, responseObject);
                    completion(response);
                }
        }];

[uploadTask resume];