How to resolve kCFErrorHTTPSProxyConnectionFailure = 310?

How to resolve kCFErrorHTTPSProxyConnectionFailure = 310?

I am getting error as followed
Error Domain=kCFErrorDomainCFNetwork Code=310 "There was a problem
communicating with the secure web proxy server (HTTPS)."
My Code is
NSString *urlString = [NSString
stringWithFormat:@"https://hostname/DEMOService/DEMO.asmx/VerifyLogin?username=duaan@companyname.ae&password=1234&AuthenticationKey=A53d3W3456dd2wdeat"];
NSURL *url = [NSURL URLWithString:urlString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL: url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10];
NSError *requestError;
NSURLResponse *urlResponse = nil;
NSData *response1 = [NSURLConnection sendSynchronousRequest:request
returningResponse:&urlResponse error:&requestError];
NSLog(@"ERROR %@", requestError);
What is error and how can I resolve it?
Thanks