This is a very intriguing problem. Every time I'll connect my MacBook Air mid 2013 with OS X Yosemite 10.10.3 to my wi-fi network at home, I can't, cause it won't be available in the list of networks available.
What I do? I turn no my Android tethering hotspot, and only after I connect to this network, my home wi-fi will be shown.
What might it be???
Best Answer
The first part is for testing.
You need to use the terminal and manually connect to it.
Turn On
Find (you can skip this if you already know the Name)
Connect
Enter/replace your WiFi name and password in the above.
This should have connected you to your Network.
In your Network settings your home network should be in the top of the list.
Open your router settings and change the network name to test if problem with naming. While in Router setting, change the channel to #5 (usually the least crowded one) to eliminate interferences.
Finally, run WiFi diagnostics, by holding the "alt" key and clicking on the WiFi icon, then selecting the WiFi Diagnostics.