A friend of mine has the same problem as Andrew with his Wi Fi dropping out on his MacBook operating on Yosemite. Perhaps Mick could detail the solution on the board so that I could 'E' mail my friend to try and resolve what appears to be the same problem.
Every time it 'drops out' he gets the message in network preferences below!
Wi Fi has the self assigned IP address 169.254.103.32 and will not be able to connect to the internet.
Many thanks Drew for your post. Mick has been in touch with me regarding this problem and it would appear that it is not quite the same as yours and has made a few suggestions. We are now waiting to see if these suggestions work.
Thanks again
John
My WIFI has been dropping out since Yosemite last Dec. Every 10 mins or so I have to switch on and off its was driving me mad. My Wife's ipad & my ipod touch are perfect. I have done everything suggested from changing location, resetting SMC (which seemed to work for a while) to clean installing Yosemite. Nothing worked until John M. told me to change my router. I wish he had told me earlier. I looked online at the top 10 for 2015. Apple router came in at No 8. So I thought that must work. What they did not say was you can't plug it into your phone. So I connected it Ethernet to my old router. Hey Presto I have milli second connection through my concrete floors every time. HAPPY ENDING.