iMac wifi disconnecting

(Sorry in advance if this is in the wrong section, only joined the forum)

My iMac keeps disconnecting from my wifi and I have to 'Turn Wifi Off' then Turn it back on.
This happens every 20 minutes. Other devices have no problems with the internet.

I was wondering if anyone knew any solutions, thanks.

Which iMac do you have (year and model) and what version of OS X are you running?

Going from 'About This Mac'

21.5inch Mid 2011 (Bought mid 2012)
Mac OS X Lion 10.7.5 (11G63)
Serial Number C02HN1EJDHJF

I hope this is what you were looking for, thanks.

OK, thanks for posting back the specs as that is important for me to answer your question.

I have the same exact machine. There were several glitches with Lion that prevented the iMac (your model and mine) from connecting back to its WiFi after waking from sleep. There was also a firmware update that was supposed to fix a disconnecting from WiFi problem.

I don't know if you installed that firmware update or not (you should have been notified by Apple Software Update) but if you did, and still have problems, I highly recommend updating to Mountain Lion.

There could also be other reasons your WiFi is disconnecting: Local interference, weak signal, etc. You might wish to download the free iStumbler application and run it. It will give you some idea of other networks in your area and the strength of your signal plus other info.

Thanks for the reply. Is mountain lion the paid app in the app store? Or is there somewhere i update to mountain lion?

I also checked and updated everything in software update, but the problem still occurred.

Yes, Mountain Lion is only available as a download from Apple through the Mac App store. It's $19.99. As I stated in my first reply, there could be other reasons your WiFi is disconnecting so make sure you explore everything. In any event, updating to Mountain Lion is recommended.

Had this very problem with my Linsksys WAG120N modem/router and identical model iMac. Replaced with a TP-Link and no more problems. Seems about three years is the average life of a router.

I've had mine for around 2 or 3 years, but I will be getting a new one soon due to new fibre broadband in my area.

I downloaded iStumbler and my wifi is only has 3 bars in the level section (not sure what I should be expecting from each section) , 39% signal, 9% noise , channel 8.
Again i do not know what I should be expecting from each section in my case, but judging by some of the sections it seems quite weak.

I will update to Mountain Lion if that is what you recommend.

Thanks for the replies.

Your signal according to iStumbler is not very strong. That may be what's causing the disconnects. Please take note that updating to Mountain Lion is not going to fix a weak signal. You may be able to improve your signal by changing the location of your router or by replacing it with a newer model. However, if you're going to be receiving fiber optics broadband soon, your ISP will likely provide a router that's designed specifically for it.