In-App-purchage not working.

In my app in-app-purchage (auto-renewable subscription) is not working. Same code is working earlier on production since last 1+ year. I check with sand box user but getting below error.

Error Domain=NSURLErrorDomain Code=-1001 "Cannot connect to iTunes Store" UserInfo={NSUnderlyingError=0x106148260 {Error Domain=kCFErrorDomainCFNetwork Code=-1001 "(null)" UserInfo={_kCFStreamErrorCodeKey=-2102, _kCFStreamErrorDomainKey=4}}, NSErrorFailingURLStringKey=https://sandbox.itunes.apple.com/WebObjects/MZFinance.woa/wa/inAppBuy, NSErrorFailingURLKey=https://sandbox.itunes.apple.com/WebObjects/MZFinance.woa/wa/inAppBuy, _kCFStreamErrorDomainKey=4, _kCFStreamErrorCodeKey=-2102, NSLocalizedDescription=Cannot connect to iTunes Store}