Level 1

21 points

Slow wifi after Big sur update

After updating to Big sur my wi-fi speeds are at about a third of what i'm used to. Right now i get something like 50-100mbit/s both ways on my macbook and 350-400mbit/s on my iphone that is right beside the computer. I'm on a 500mbit connection and I use the same 5ghz network on both devices. Before updating I got the same speeds on both devices.

I have tried everything from this guide: https://osxdaily.com/2020/11/23/how-fix-macos-big-sur-wifi-issues/

Any other ideas?

MacBook Pro 13″, macOS 11.1

Posted on Dec 21, 2020 1:02 PM

Top-ranking reply

Artsakh7

Level 1

10 points

Posted on Apr 5, 2021 2:11 AM

Guys I think I may have found a solution for this problem.

Turn off bluetooth.
Disconnect all peripherals from your computer.
Open System Preferences. In the "Energy Saver" preference, de-select "Wake for network access" (no check, and leave it that way).
Open the finder. Select the "Go" menu. Select "computer." Select "Macintosh HD." Go the the "Library" folder. Go to the "Preferences" folder. Find the preference file "com.apple.bluetooth.plist."
Rename "com.apple.bluetooth.plist" as "com.apple.bluetooth.plist.old" (i.e. add ".old"). Eventually, if this solution works for you, you can delete this "old" preference file.
Restart your computer (this will create a new "com.apple.bluetooth.plist" preference file).
Turn bluetooth back on.

Apparently, the problem is a bug caused by a bad interaction between the bluetooth preference file and wifi.

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Similar questions

58 replies

Mar 22, 2021 1:52 AM in response to MoonJ.

Since I have instaled Big Sur last week on my iMac (Retina 4K, 21.5-inch, 2017) I have moved from an ethernet connection that had 800Mbps to 200/250Mbps on a 1Gb/s network.

I have a MacBook pro 15 (early 2011) that is not running Big Sur and the ethernet connection is still on the 800Mbps.

This issue 100% sure related with Big Sure and Apple is looking sideways and trying to point in different directions instead of looking to the actual cause (Big Sur) on this issue reported by many many users!!!

I had a perfectly working ethernet connection and with screenshots to prove it from the before and after big sur.

Before:

After:

Big Sur changed the ethernet connection, nothing else!

Ranjumk

Level 1

4 points

Mar 21, 2021 11:10 AM in response to jens8553b

For me the wifi disconnects randomly after upgrade to Big Sur! Looks like the 5Ghz freq in this release is broken because when I switched to a 2.4Ghz wifi it works fine.

FA-RO

Level 1

13 points

Jan 11, 2021 10:54 AM in response to rushu25

Hi! I'm glad I found this thread. I'm having exactly the same issue. Running macOS 11.1 (20C69) Wifi speeds are much slower (only one third or one half of the speed on all my other devices). But the strange thing is: It happens only after some time. Directly after reboot I get full speed of 500-600mbps. But then after 5 to 10 minutes I'm only getting about 150-250mbps. Then nothing can bring back the faster speeds.

Tried everything:

resetting PRAM/SMC
completely removed wifi adapter under network settings and added new one
removed wifi preferences
I'm not using any firewall/antivirus-software
changed wifi 5ghz channels, MTU size, CTR threshold
optimized all settings on my router
killed all background processes and unnecessarily running apps
disabled timemachine backup

Nothing is working. But all other apple devices in this house (two iPhone 11 Pro, iPad Pro and so on) get 500-600mbps very single speedtest. Just my mac doesn't get the full speed. And honestly this was by far the most expensive Apple product I've ever bought (2849€). So that's driving me crazy...

We need a fix for this problem!

sterling r

Community Specialist

Jan 20, 2021 8:18 PM in response to jens8553b

Jens,

Great information! With the alerts you're seeing in Wireless Diagnostics, use the following resource to help with the settings for your wireless router. You may also need to work with your internet service provider for help with the settings: Recommended settings for Wi-Fi routers and access points

Let us know how it goes.

Cheers.

blujez

Level 1

4 points

May 24, 2021 10:39 AM in response to DarthHodor

Weirdly, it did work for me and now it seems be recurring. Might have been a freak system clash but by turning off wifi earlier, then bluetooth, then wifi back on, then bluetooth it seems be fine again.

God knows what the root of it is but it's doing my ******* head in.

Jun 24, 2021 4:51 PM in response to rmpoole1

I switched to a usb wired mouse. Takes a port but works great

chuck_3rd

Community Specialist

Feb 2, 2021 7:04 PM in response to jens8553b

Jens,

That's great to know! Since the issue happens with uploading to your NAS too, we recommend reaching out to your internet service provider to have them look into things on their side. If they don't find any issues, reach Apple Support to look into this more. They can be reached here: Get Support

Thanks again, and have a wonderful day.

May 17, 2021 1:21 PM in response to jens8553b

guys did the last system (11.3.1 (20E241)) and safari update ( Version 14.1 (16611.1.21.161.6) ) resolve your problem? i think yes because now i have finally full speed again without trying to fix it.... ???

urbfood

Level 1

4 points

Jan 27, 2021 8:42 AM in response to MoonJ.

I tried everything above with Apple tech, with no resolution of my problem. I'm getting ~8-10 Mbps download speeds on my MacBook w/Big Sur and ~100Mbps on my other macs running Catalina. This is a glitch that has occurred after updating from 11.01 to 11.1.

jens8553b Author

Level 1

21 points

Feb 2, 2021 2:34 PM in response to jens8553b

Oh i tried uploading some files to my NAS as well. The NAS is connected to my router by cable and i used the wi-fi for my computer.

It did 10gb in 5 minutes which would be something like 260mbit/s if i'm not misstaken?

Could it be that my problem only occurs with external traffic?

clb5

Level 1

10 points

Apr 25, 2021 9:41 AM in response to thoggs

I've been having the same problem on MBP. After a few days, wi-fi speed slows across all browsers. I need to reboot the system to restore to normal speeds. Other devices are not affected.

Artsakh7

Level 1

10 points

May 17, 2021 11:39 PM in response to BachyWachy

Can you check what frequency your router is using? if it's 2.4GHz try switching it to 5GHz, I've tested it on multiple devices and they are all working flawlessly now

rushu25

Level 1

8 points

Dec 24, 2020 11:56 PM in response to jens8553b

I have the same issue. In my case, I bought the M1 (upgraded from MacBook Air 2013 running on High Sierra). The file transfer speeds over the network have drastically reduced when on WiFi. The same issue doesn't happen with ethernet. Tried all the possible tweaks adjusting the Wifi 5Ghz channels and width on the router but no change in the file transfer speeds at all.

jens8553b Author

Level 1

21 points

Jan 19, 2021 1:04 PM in response to MoonJ.

Big thanks for your reply!

I have narrowed it down to bad speeds in regular mode and my regular good speeds when i'm in safe mode. I did also do the same tests on my partners macbook pro (same model, a bit newer) that is still on Mojave (10.14.6) and get the almost the same results (bad speeds in regular mode, but not as bad as on mine, good speeds in safe mode). The problems on my macbook did not occur until i updated to Big sur though..

What might be the next step?

Best regards

Jens

jens8553b Author

Level 1

21 points

Jan 20, 2021 2:31 AM in response to chuck_3rd

When using the test user account i got bad download speeds and great upload speeds for a couple of tries. After that i got the same results as with my regular account.

The Wireless diagnostics got the following results:

Safe mode

Wi-Fi channel overload

Regular mode

Wi-Fi channel overload

Fundamental connection error

All of the above errors are still there after rebooting the router. I have a total of 4 units connected to my wifi (iPhone, MacBook and two Sonos speakers) and 2 units connect by ethernet cable (NAS and tv). None of the other units is that active (NAS mostly 1-2 kb/s up/down).

I’ve also made sure that the routers wireless channel mode is set to auto

I did not have any Start up objects to remove

I added a new network location and did a wireless diagnostics which got me the fundamental connection error but no channel overload

Jens

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Slow wifi after Big sur update