MacBook loses wifi connection after sleep

[SOLVED]

I had exactly the same issue with MacBook Pro 2016. After waking up from sleep, it sometimes needed from dozens of seconds to couple of minutes to reconnect to my home WiFi network. During this period WiFi icon was showing that WiFi is connected but WiFi actually didn't work.

I tried many different tricks such as specifying fixed channel number on router, lowering WiFi speed from 150 Mbit to 65 Mbit, forcing long preamble, playing with fragmentation threshold etc. No success.

Then I found this article: https://cafbit.com/entry/rapid_dhcp_or_how_do. It looks like modern versions of MacOS use some tricks to speed up reconnection to the network after sleep. Instead of doing fair procedure of discovering DHCP server and obtaining IP address from it, MacOS just pings (by MAC addresses) several DHCP servers it last used. This approach may significantly speed up WiFi reconnection.

The problem is that most (usually all or all but one) of the DHCP servers MacOS tries to ping actually do not exist in the current network, so from router's point of view MacOS sends in a quick sequence several packets to non-existing MAC addresses. My router treated this as at attempt of DoS attack and blocked my MacBook for several seconds.

Once I disabled DoS protection on the router the problem gone. BTW, this also fixed problem with my printer connected over WiFi, that was loosing WiFi connection.

You'dthink wifi connectivity would be one of the pillars of a high end notebook

My Macbook Air retina loses wifi every wake from sleep since the "recommended" upgrade to Sierra

Sometimes I get the "no hardware installed" icon just for added interest

I have tried all the fixes including OSX re-install

It has made me very sad

I have a 12 inch MacBook (2015) as well - and I am seeing the exact same problem.

I haven't tried turning wifi off/on - mine works after a restart of the computer. I have iPads, iPhones and another MacBook Pro on the same network without problems.

My MacBook is running El Capitan and my network is on a Verizon wireless router. Running wifi diagnostics tells me to review Wifi best practices, that I am using a crowded wifi channel and that I have LAN connectivity failure.

Would love to hear whether this is a know problem with the MacBook.

My next step: I can certainly believe the crowded wifi stuff as I am seeing my AppleTV have intermittent problems streaming movies once in a while. Will try to find a way to move to a less crowded channel in my 200+ apartment building.

Claus

Please test after taking each of the following steps that you haven't already tried. Stop when the problem is resolved. Back up all data before making any changes.

1. If possible, test on at least one other network, such as a public hotspot or the hotspot created by a mobile phone. Some Wi-Fi routers are not fully compatible with some Apple devices.

2. Make sure the network is on the preferred list by following these instructions. It's important to read the article carefully, as it's the starting point for any further efforts to solve the problem. If you skip any of the steps, the problem may not be solved. Make sure the box marked

Remember networks this computer has joined

is checked.

3. Follow the instructions in this support article under the heading

Symptom: After restarting or waking from sleep, my computer might not connect to the Internet

4. Reset the PRAM.

5. Make a note of all your settings for Wi-Fi in the Network preference pane, then delete the connection from the connection list and recreate it with the same settings. You do this by clicking the plus-sign icon below the connection list, and selecting Wi-Fi as the interface in the sheet that opens. Select Join other network from the Network Name menu, then select your network. Enter the password when prompted and save it in the keychain.

6. From the Location menu at the top of the Network preference pane, select Edit Locations. A sheet will drop down. Click the plus-sign button to create a new location. Give it any name you want. In the new location, set up the Wi-Fi service with the same settings you used before. Click Apply and test.

7. Launch the Keychain Access application. Search for and delete all AirPort network password items that refer to the network. Make a note of the password first.

8. Repair permissions on the startup volume.

9. Turn off Bluetoothand test.

10. Reset the System Management Controller.

11. This step shouldn't be necessary, but has been advised by Apple Support in some cases, apparently as a workaround for a bug. Open the Energy Saver pane in System Preferences. If applicable, click the padlock icon in the lower left corner to unlock the settings. Enter your administrator login password when prompted.

Select the Power Adapter tab and uncheck the boxes marked

Wake for Wi-Fi network access

and

Enable Power Nap...

if present. Then, if the computer is a MacBook, select the Battery tab and uncheck

Enable Power Nap...

12. Reinstall OS X.

Thank you, Linc. I am working my way through the list now.

Claus

I have the exact issue .. Macbook with el Capitan OSX.

Let me go thru the PRAM reset thing.

Ok after resetting the NVRAM it looks like the WIFI is coming back normal after sleep.

I will try several times but I think I'm good now.

Thanks all!

Hi Linc,

I did steps 1-4 (the PRAM reset).

However, I have a small suspicion that MS Outlook 2016 may be involved. Outlook was open and looking for mail everytime I woke my MacBook from sleep. There seems to be a lot of complaints about that particular piece of software. Right after the PRAM reset, I also updated Outlook to 15.14.2.

So far no recurrences - I did not test in detail whether things worked after the PRAM reset alone or whether it was the combination including the Outlook update that did the job. Sorry.

Claus

Same issue. The problem is, APPLE, that my new computer literally did this right out of the box (2015 13" MBP Retina). I have a 5 year old samsung phone that doesn't have this problem. My last macbook pro (2010 model) had wifi issues too. What is the deal apple? Why should we have to look for a fix for a brand new computer? Why was this issue not fixed in El Capitan? Its obviously a widespread problem. It's the first thing that comes up on google search when you type in "Macbook wifi"

For those like me who are a little risk-averse... an easy workaround (on my machine, anyway), is to just open the Network panel on System Preferences after waking up. That's it - just wait a few seconds for it to get connected. Definitely a nuisance, but maybe Apple will fix this sometime, so we don't have to enter a 12-step recovery program.

Saw today the newest update of el capitan "fixed some wifi issues". NOPE not this one, one of the most widespread problems...smh

My machine is a MacBook Pro (Retina, 13-inch, Late 2013) running

I've had exactly the same problem described in previous comments since Day ONE! I've tried most of the proposed fixes to no avail.

My wife and I both bought 12" Retina MacBooks and we are both having issues. I have the 1.3 and my wife the 1.1...her problem happens less often, mine more.

It can last weeks. I love my computer but this is getting annoying. A few things on the list above yet that I can try.

Mostly just venting.

Same Problem here. Brand new MacBook 12". Did try anything what Apple support told me, including a total reset. Nothing works.