Q: when streaming a movie from iphone 4s to apple tv, wi-fi keeps disconnecting.

Hello 1911ojb,

It sounds like you are streaming video from your iPhone to your Apple TV with Airplay, but either the phone loses Wi-Fi signal when you do, or the playback from the Apple TV disconnects intermittently. If the former, I would use the following article to troubleshoot the connection between the iPhone and your router:

iOS: Troubleshooting Wi-Fi networks and connections

http://support.apple.com/kb/TS1398

If the latter, I would use the following article to help troubleshoot the Airplay connection:

iOS: Troubleshooting AirPlay and AirPlay Mirroring

http://support.apple.com/kb/TS4215

This section in particular:

Troubleshooting performance issues with AirPlay or AirPlay Mirroring

Thank you for using Apple Support Communities.

Take care,

Sterling