wi-fi issues

Hello,
I'd like to know if someone experienced these strange problems. I have a macbook 2011 15'. Two months ago I replaced the motherboard (radeon gate). After I got it back I installed yosemite and I had intermittent wi-fi issues... for example, the wifi appeared as connected, but could not load any page. Turning it off and on again sometimes worked, other times the wifi wouldn't turn on again. But a restart fixed it, only to have the issues again after some time. Other times, a restart would not recognize the wifi card ( no hardware installed message). So, i downgraded to mavericks from a time machine backup, but these problems persisted. Just to be clear... I didn't have any wifi issues before the update to yosemite. I've done everything I found on the net, like switching locations, deleting the wifi preferernces, recreating the wifi, etc, except a clean install. I mean, if it didn't work from the backup (when everything was fine), will a clean install work? I have 3 other macbooks in the house, one with yosemite and two on mavericks... only this one has these problems. Anyone know what is this? I don't believe it's the wifi card, because sometimes it works... also... I have no prblems with bluetooth. thank you

 

hi
thx for the reply
I know that yosemite has issues, but why did I have these problems when restoring from time machine? this is what puzzles me... when I did my last backup, I had absolutely no problems with wifi

 

well, I didn't have any wifi issues on mavericks or prior, and I've done my last backup before upgrading to yosemite. while initially I blamed yosemite for the issues, when I restored from time-machine, the same thing happened... so I don't know if it's the wifi card (but shouldn't I have problems with bluetooth too?), or something else... I've done a clean install of yosemite yesterday and still those problems appeared after 2-3 hours

 

somebody knows what's this about?