Wi-Fi Problem - Strong signal, good noise, yet nothing works

[BeSweeet]

See this screenshot:

I'm using a 2012 MacBook Air (max connection rate of 300Mbps) and an ASUS RT-AC68 router. As you can see above, the signal is very strong, there are no problems with noise, yet the transmission rate is just 7Mbps, and at this rate, nothing works. Can't even load the router's web UI, or get reasonable local ping times to it. Something similar actually happens on my iPhone 6 Plus.

I narrowed it down to three things:
1) Monday's 10.11.4 / iOS 9.3 updates
2) Router problem
3) Hardware problems

The router has been acting normal for a long time. Adjusting the wireless channels and rebooting it didn't seem to do anything.

I'd say that my MacBook Air's Wi-Fi/BT card is just having problems, but my 6+ has started doing it as well...

And none of this happened until very recently, coinciding with the release of 10.11.4 and iOS 9.3.

No idea what to try at the moment.

 

[Shirasaki]

Maybe, you can try to switch 5Ghz back to 2.4Ghz, and see what it will happen.

 

[mb87]

Similar problems here on a 2012 Macbook Pro and iPad Air immediately after upgrading to 10.11.4 and 9.3 respectively.

Mac will intermittently connect to wireless at 5GHz, very slow if a connection is made. No problems at 2.4GHz.

iPad connects but is intermittently slow/flakey at 5GHz, no problems at 2.4GHz.

 

[BeSweeet]

Similar problems here on a 2012 Macbook Pro and iPad Air immediately after upgrading to 10.11.4 and 9.3 respectively.

Mac will intermittently connect to wireless at 5GHz, very slow if a connection is made. No problems at 2.4GHz.

iPad connects but is intermittently slow/flakey at 5GHz, no problems at 2.4GHz.

Exactly the same here for 5GHz vs. 2.4GHz. I've been using all the 10.11.4 and iOS 9.3 betas, and never had issues until the final releases.

 

[John Mcgregor]

Something like that for me as well. Since all other devices work normally i attribute this to the OS X update.

 

[br0adband]

What I noticed after the update on my 2011 MBP is - for whatever reason - when I click the icon in the menu bar I only see 3 networks, not the 25+ I'm normally used to seeing. Even in the Network preferences pane it's only showing 3 networks at a time - if I open System Report and look at the Wi-Fi info it'll show most of the networks I should be seeing when I click that icon but don't. Only thing I've done in the past 48 hours to this laptop is install the 10.11.4 update so I have no idea what's going on. It's not an issue for me yet since I don't do much traveling with this machine aka it's showing me the home network as expected but, the fact that I don't see that huge list of networks I'm so used to seeing is making me wonder what's going on.

If I boot to the recovery HD and then check the networks it shows all of the expected ones, I'm only seeing this behavior when I'm in 10.11.4 itself. Might have to get a spare hard drive and do a clean install of 10.11.3 here shortly and do some testing but, it's somewhat odd at this point why this is happening now and not prior - I was using some of the 10.11.4 betas prior to the final update and none of those exhibited this behavior.

Another thing: the Wi-Fi system report is only showing 11n networks - I should be seeing several 11g APs (provided by my apartment complex, they haven't updated to 11n hardware) and they're not visible either anymore.