My wireless network connection gets lost frequently (OS X 10.10.2)

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.