I have long periods of time with no working internet because my 802.11 wlan connection gets lost frequently. This only occurs on my Mac. It runs OS X 10.10.2.
When showing the desktop after starting up the computer, the wifi symbol in the superbar shows the network searching for a wlan connection. Very often, every other startup or so, it won't find the connection to my wifi network. Turning the machine off, plugging the power cable for 20 seconds, plugging the cable back in, wait another 5 seconds and turning it back on usually helps.
I don't have any connection issues with the Windows PC or the iPad, it's just the Mac. Checking the web shows some talk about wireless lan driver issues with Macs (Update from 10.10 to 10.10.1 and then to 10.10.2) with nothing really having changed for my Mac.
I've called Apple service, they have a set of procedures they apply, but that doesn't fix the issue permamently.
I tried plugging in another wlan adapter (actually two different ones) and use it instead of the onboard device, but OS X didn't seem to recognize the devices.
I'm somewhat at my wit's end about the issue.
Best Answer
I have struggled with my own connection dropping intermittently (more often, just becoming very slow/weak for periods of time). The problem for me seems to be that I chose a spot in my house that has poor Wifi signal, perhaps due to the configuration of walls, the configuration of metal in my house construction, and so on. If I move my computer a meter or two to the left, the problems go away.
Also, the problems are much worse for a Mac laptop whose lid is closed. The antenna is located in the hinge, and with the lid closed, the antenna's ability to receive signal is reduced by half.
I don't know exactly why wireless signal strength changes over time, causing intermittent problems. Could be the use of electronic appliances in my house or someone else's. Could even be solar radiation changing when clouds go by. Best thing to do is get your router and computer jointly located so that the signal strength is generally strong - then fluctuations won't cause you to get accidentally dropped.
To check out your wireless signal strength and see how it varies when you move your machine around the house, follow this link:
http://letstalk-tech.com/how-to-access-the-wifi-scanner-in-mac-os-x-yosemite/