I've been getting constant UNet dropouts for a basic networked scene (two player transforms and the occasional RPC). The connection drops due to a timeout.
Connections reliably drop within 5 minutes, and mostly within 30 seconds. I've read online that UNet does this a lot. I've tried increasing the NetworkDropThreshold and OverflowDropThreshold up to 90%. I also put the ping timeout up to 5 seconds.
Any ideas on how to fix it? I'm using wi-fi for both players, and I'm on Unity 5.6.0f3.
Upgrading to Unity 5.6.1f1 fixed these issues. While there are no comments in the release notes, or any of the patch notes for the 5.6.0 series, the difference in reliability was astounding, at least for me.
If you're experiencing issues, try the latest version. While the latest stable release worked for me, you can find the latest patch releases at: https://unity3d.com/unity/qa/patch-releases.
If you're using Unity's Matchmaker, there is a hard bandwidth limit that kicks players, and it's expensive. Photon is good alternative for networking: https://www.photonengine.com/PUN.