The Wi-Fi connection between your iOS devices and SYC2 is dependent on Bonjour service by Apple. While trying to solve connection issues, please make sure no security software is blocking Bonjour in the first place.
If your PC is connected to your local network via ethernet, you may need several more configuration steps for Bonjour to function, and they depend on your environment. Read the following thread if you need more details: https://discussions.apple.com/thread/5092691