AirDrop not working on ALL Wi-Fi networks
The basic things to do are turning On and Off Airdrop, upgrading your Mac to its latest OS, reset the Network Settings on your iPhone, and adjust the FireWall settings on your Mac. Doing one or more of those should help you fix the problem.

Source: http://appletoolbox.com/2016/02/airdrop-not-working-7-tips/