macOS Catalina

issue with OS X 10.15.3 / MacBook Pro 16 : 5Ghz WiFi Band disappear after closing the lid or turning off WiFi then back on

Issue on MacBook Pro 16 with WiFi 5ghz

I start my MacBook pro, then I login and I’m able to see both the WiFi 2.4 ghz and the 5ghz bands of my wireless routers.

I’m able to connect to both.

On the 5ghz I connect at 1300mbps

Speedtest show great sustained throughput.

So far everything fine and normal.

The issue appears whenever I :

  • Close the Lid of the MacBook Pro, then Open it Back
  • Or
  • Turn OFF the WiFi and turn it back ON from Wireless menu

The 5ghz band disappear from the available networks.

The 2.4ghz band keep showing and connecting as usual.

The only way to fix the above issue is to restart the Macbook Pro

Sometimes a restart or multiple restarts don’t fix the issue.

When the issue become persistent, the only way found to restore the 5ghz band is to 

Close any apps that use the network. 

Turn off Wi-Fi

Go to Macintosh HD/Library/Preferences/SystemConfiguration/

then Delete all of the network-related files 

    • com.apple.airport.preferences.plist
    • com.apple.network.eapolclient.configuration.plist
    • com.apple.wifi.message-tracer.plist
    • NetworkInterfaces.plist
    • preferences.plist

then Restart

This would fix the problem, temporarily.

Until i close again the lid of the Mac. (or power cycle the WiFI OFF then ON)

I have formatted my Macbook Pro and installed a fresh and last version of MacOS Catalina 10.15.3

With nothing else installed. No apps. Nothing.

And the issue stay the same as described above.

I have 2 routers, one at office and one at home.

Different Brands and Models – both dual band 2.4 and 5 ghz

– ASUS RT-AC68AU at the office 

– Mikrotik hAP-ac – RB962UiGS at home

Tested on both and issue is the same on both.

Finally just to make sure the issue is not the Routers,

1 . I tested my WiFi with my iPhone 11 Pro, and there’s no issue with 5ghz or 2,4ghz with the iPhone.

2. I tested using Bootcamp with Microsoft Windows 10 Professional on the same MacBook Pro 16

There is no issues with the 5ghz band. 

I can Turn Airplane Mode ON. WiFi OFF then Back ON.

I can close the lid of the MacBook Pro, then open it back and log back in.

No issues whatsoever with 5ghz WiFi on bootcamp with Windows 10

Other things tried :

– I already reset the PRAM and the SMC multiple times. NO FIX to this issue.

– I booted the Mac in safe mode, NO FIX to this issue.

– When booting in recovery mode, (to re-install MacOS) this issue doesn’t appear. 

  We can turn OFF WiFi, then Back ON and the 5ghz band will appear all the times.

  And connect and works.

I did have open a case with Apple, on February 7, 2020, and I spoke with a senior support consultant.

He made me download a diagnostic tool, with which he captured the session, with the issue.

Then mail it back to Apple, for further troubleshooting.

So far Apple support team have been, very good, and easy to get in touch with.

The Apple Techs Guys were very good, and patiently checked and double checked everything.

Overall, Excellent support and Attention. 5 Stars.

I called back, to follow up, but they haven’t got me an answer on this issue yet.

Still waiting a Fix, on that End.

So to recap : 

– WiFi 5ghz disappearing issue after sleep mode : only installed OS X 10.15.3 catalina (fresh install)

– WiFi 5ghz no issues on Windows 10 Bootcamp / OS X 10.15.3 from Recovery mode.

So the issue seems to be Software related, probably a bug on the Wireless Drivers in MacOS Catalina.

If anyone have some idea on what can be done to fix this, will be greatly appreciated.

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