Q: Wifi is incredibly slow on OS X El Capitan

This worked perfectly for me! (At least until now) Yesterday, out of nowhere, my mac air with El Captain's WiFi started to be amazingly slow. It wouldn't load not even google webpage. After removig all the apps that were set to start automatically with the system, my WiFi speed was back with full power. I don't know which APP was causing the problem, but I had Drive, Evernote, Dropbox and some others. I didn't even had to reboot the mac

Finally!

Thanks very much

So I am having a similar issue.  Life was fine for a while after updating to El Capitan and then all of a sudden my macbook pro wouldn't connect.  I was getting full bars like it was fine, but the wheel kept spinning and I would eventually get the no connection message.  Whenever that happened all of my other devices would have the same problem...my other macbook, ipad, phones, everything.  They would all show full connection but wouldn't actually connect.  The only thing that would connect was my windows work laptop.  I would restart the router/modem and bam...good to go.  Then after an hour or two the same thing...but only when trying to use my macbook pro. 

I gave up and bought a new router.  Set it up with my wife's macbook...all is fine.  Connected my ipad and phones.  All is fine.  Connected my macbook pro and bam...same problem.  Network goes down for all devices except window laptop.  What in the world is going on? 

Here's what I did to resolve the wifi dropout issue. I tried the OSX Daily recipe but it didn't work. This is just a more comprehensive version of it. instead of deleting some of the files in the SystemConfiguration folder, just delete (or back it up) the whole folder and reboot. OSX will rebuild the folder. The issue is from updating and not clean installing El Capitan, so some of the old setting are left over. A clean rebuild of this folder seems to fix it.

The folder is in HD/Library/Preferences

There is probably a similar rebuild option for Bluetooth, but I don't know what it is. Apple should really sort out these issues when installing a new OSX over an old one. It wouldn't be that hard.

I tried many of the things on this thread and more:

Reseting SMC and PRAM

Clearing Browser Cache

Removing and remaking Airport connection

Booting into Safe Mode

Sadly nothing worked so my best solution has been to place a WiFi extender next to my Mac and use the built in Ethernet port. Airport is switched off now and using wired LAN is back to normal speeds. I hope that idea might help someone and let's hope for a fix in 10.11.2

Tried the same things too, none of it worked..

I think the only problem is when the router is set to AC mode, with 80Mhz bandwidth.. Though it gives higher Mbps, but the range of it is weaker! The problem here now is that when the signal gets weaker, the Macbooks/iMacs find it more difficult to have a stable connection, due to El Capitan update of course..

To confirm this, I put the router mode to N with bandwidth 40Mhz and this gave me stable connection everyday..

Yesterday though, I figured I'd try to extend my wireless (with AC mode and 80Mhz) using a repeater, to give stronger signal around the house. Surprisingly, this worked! Now I'm connected to 5Ghz band with AC mode and 80Mhz, and it had been stable ever since!

To conclude, the problem is how the Macbooks/iMacs with El Capitan, handles wifi with weaker signals. I hope some of you can also try this to confirm if this really is the issue.

I suspect my router problem is different.  However, it seems likely that my problem was fixed today via an Apple wi-fi specialty tech support person. 

My MacBook (new 12") was going dropping into a ½ speed mode sometimes after sleep.  My crude fix was to click on the wi-fi logo on the upper right and turn wi-fi off and then on.  My connect speed is 50 mbps at the wall.  I use an Apple airport extreme router and an Airport express extender.  Using the same wi-fi logo on the upper right at the same time pressing the option key, you can see more wi-fi info.  I noticed when my MacBook was slow it was on channel 11 (2.4Ghz) and when it was fast it was on channel 52 (5Ghz).  Using airport utility (find by using spotlight and key in air) i could see my network.  I had to reset the Airport extreme to 5Ghz.  Then reset my Macbook to seek the 5Ghz version on my router using the Wi-fi utility.  Hopefully, I will now continue to receive wi-fi at 48 mbps vs. 24 mbps.

Has anybod installed the new 10.11.2 beta? Does it fix the wifi issue?

I just upgraded to the BETA 5, the wifi on my MacBook Air is still slow.  I have run through most of the suggestions here in this thread, but no luck.

That's a shame. I was hoping Apple was working on this. Thanks for letting us know.

robinfromköln wrote:

 

That's a shame. I was hoping Apple was working on this. Thanks for letting us know.

This is a very long thread, so long that it is almost impossible to keep track of.

Different people have had different problems for different reasons, but most people are having no problem at all.

It is reasonable to expect a fix when there is a clearly identified bug, but it seems that people are somehow hoping that an update will fix something that is not clearly defined, and is more likely caused by conflicts with old software on their machines, rather than a bug in OS X. Those people are going to get disappointed.

I recommend that if you want to get an issue resolved, start a new thread giving detailed information about your problem, your setup, steps taken to try and fix it. Maybe people on this forum can provide specific insight.

Yes you are right - as I mentioned earlier:

I can understand that some systems have problems after an upgrade.

But in my case (and that's also the case for other people here) we are talking about a clean install and that's why this is certainly a bug, since no third party software is installed.

Cheers

My system specs:

MacBook Pro (15-inch, Early 2011), 2,2 GHz Intel Core i7, 16 GB 1333 MHz DDR3, 256 Crucial SSD

I recently installed a new modem to achieve increase speeds from Cox Ultimate service (i.e. 300 mbps down and 30 up). As a result, I frequently check all my equipment to ensure these speeds were coming in. After a couple days, I noticed my 5K iMac would sometimes slow down to speeds 1/3 of what it should be. I also realize by simply turning off the wifi and then back on, the speeds would restore. I haven't tried any of the fixed yet documented in this thread. I am a bit bummed.

This seems to have helped me out too. Thanks very much jubamad!

Even after going all the way up to Mac OS 10.11.2 El Capitan, I spent a half day trouble shooting wifi connectivity issue. I finally powered up my old laptop and realized the wifi network was up and running well just not with Mac OS 10.11.2 El Capitan. I found an excellent youtube video on how to fix the issue. Worked for me. video at youtube  https://www.youtube.com/watch?v=-eCxgPiTb5s

I've been there and done that (video recommendations)... my network remained slow, and in fact has been far worse since Apple published its update.  I wish I could do the system reinstall, but that requires a network connection, and Apple's notwork won't support the installation requirement.

I find the WiFi fiasco as worse than Windows' Vista ... a watershed moment when I finally discarded Windows.  IOS launches have been nearly as destructive.  Cook does not seem to get it: people have choices.  As I see it, Apple is probably not far from collapsing in a manner not unfamiliar to us: the collapse of Microsoft.