Since installing Yosemite I've had no Wi-Fi at all and just have a "Wi-Fi: no hardware installed." message. I even bought a USB Wi-Fi dongle to no avail.
Do you think this will fix the problem?
Disclaimer: I know nothing about computers, I tried resetting SMC but this did nothing, beyond this I'm lost...
I recall having this message at some point. I'm trying to remember exactly when, but, I think a clean install of OS X fixed this. But, here are some things to try:
Try repairing permissions, then restart (probably won't help, but, possibility.)
Have you tried disconnecting all peripherals? Shut down mac, take everything out of any USB or other ports, start up. Sometimes a bad external hardware device or even a bad cable can cause oddities with something seemingly unrelated.
I would try a clean install of Yosemite. ...When you say you reset SMC, you mean PRAM? If not, restart your mac holding down command, option, P & R, wait for restart sound a 2nd time, then let it boot up. I would do this just before a clean install.
If this doesn't work, you will need to run apple hardware test, depends on your mac as to how to do this.
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While I would normally agree with you, it truly made a difference with our Macs, Apple TV's, etc. Someone else on the forum suggested it as a possible fix, and it had the desired effect in my example.
We have a couple of Mac Mini's, wired, with static IP addresses running Server app. They needed rebooting at least daily in order to be seen by the other Macs and iOS devices here. After enabling link-local only on the IP6 side of things, they have been rock solid networking wise.
My wife's MacBook Air has had no issues since enabling link-local.
Makes no sense to me either.
Interesting. I see the settings are set to Automatic by default, yet, I know my modem does not support IPv6, so, it seems like changing to link-local could keep it from trying to use IPv6. I would think, if your ISP or your modem does not support IPv6, you would want it turned off so it isn't trying to use it. I know how Apple can be, they automate things so that it keeps trying the best option.