Here's a couple of questions to start off:
- Is the iOS/firmware/software for your iPhone as well as the Apple TV fully up-to-date?
- What is the version of SlingPlayer for iPhone you are currently running?
- Are there multiple routers in the home with the Apple TV?
- Does the SlingPlayer stream fine on the iPhone when not Airplaying to the Apple TV?
- What is the Quality set to on the iPhone prior to the handoff to the Apple TV?
Also, it appears as though TCP (Transmission Control Protocol) is passing with your Slingbox therefore, you should not need to set up any port forwarding.
Sling Media Forum Moderation Team