Wi-Fi is unstable after macOS Tahoe update on MacBook Air

Shade of Blue wrote:

the same stupid behavior. So it's a user account issue that persists across volume migration.

So the only possible solution I can think we're left with is to create a fresh new user account and manually transfer over every single thing, which I'd very much rather NOT do, that sounds incredibly annoying.

OR to start going through every single random user Library folder and wiping out everything we can in the hope we catch the culprit??? That sounds equally bad.

... / genius bar people telling me to wipe and reinstall my OS for the 10th time.

Maybe you have fixed this by now. But it seems that the migration step is bringing over a setting or configuration that creates the problem. Which you avoid by creating a new user. So don't manually transfer everything, and don't go through the Library folder deleting this or that. Instead, you could do this (this is like a nuclear option but you may need this):

• Make two or three verified backups. Restore some random files and folders to verify.
• Follow Apple's instructions for preparing a Mac for transfer or sale. This will completely wipe the Mac and install a fresh MacOS.
• Create a new Admin user, with a different name than any used previously. Do not install anything. You now have a "brand new" Mac. Update to the latest version of MacOS. Now test. If the problem is present, you have a hardware problem.
• If the problem is not present, you can now run Migration Assistant and from one of your backups migrate over ONLY your user account and files/folders, no Settings, no Network Settings, no Applications, no "Other." Now, before installing anything, retest for correct networking performance. If it works properly, you can then install one or two at a time, trusted software with the latest installers. Do not install any networking, network monitor, antivirus, VPN, "cleaning tools," or such things. Leave all cloud storage off and deactivated for now.
• Retest. If ok, then activate any cloud storage systems, one at a time, test after each activation.
• Bit by bit, bring your Mac back to where you want it to be set up, testing after every 1 or 2 installs.
• If the problem is brought back after the Migration Assistant step, then start over but manually copy (with Finder, no Migration Assistant) all your Documents, Desktop, Downloads, Music, Pictures, Movies folders from one of your backups. Don't copy over anything from your user Library. If you have Apple Mail in there that you need, you can manually bring that over later. After the manual copies, retest.

You could also try these

Forget your Network and delete the Wi-Fi configuration files

Go to System Settings > Network > Wi-Fi, click the three-dots button next to your network, and select Forget This Network.

From the previous tip in the thread

To reset network preferences on a Mac by deleting .plist files, disable Wi-Fi, open Finder, press Command+Shift+G, enter /Library/Preferences/SystemConfiguration/, and delete files like com.apple.airport.preferences.plist, NetworkInterfaces.plist, and preferences.plist to the Trash. After restarting the Mac, your system will regenerate these files with default settings. 

Steps to Reset Network Preferences

1. Turn off Wi-Fi: Click the Wi-Fi icon in the menu bar and select Turn Wi-Fi Off. 
2. Open Finder: Click the Finder icon in your Dock. 
3. Use "Go to Folder": Press Command+Shift+G to open the "Go to Folder" dialog box. 
4. Enter the Path: Type or paste /Library/Preferences/SystemConfiguration/ into the box and press Go. 
5. Delete .plist Files: Locate the following files in the SystemConfiguration folder and drag them to the Trash: 

• • com.apple.airport.preferences.plist
  • com.apple.network.identification.plist (if present)
  • com.apple.wifi.message-tracer.plist (if present)
  • NetworkInterfaces.plist
  • preferences.plist

1. Empty the Trash: Right-click on the Trash icon in the Dock and select Empty Trash. 
2. Restart Your Mac: Go to the Apple menu and select Restart. 
3. Re-enable Wi-Fi: After your Mac restarts, turn your Wi-Fi back on from the menu bar. Your Mac will automatically create new default .plist files, and you'll be able to reconnect to your network. 

Reset your Location Services 

1. Go to System Settings > Privacy & Security > Location Services.
2. Turn off Location Services.
3. Next, restart your device from the main Apple menu.
4. When your Mac relaunches, turn your Location Services back on.

Use Terminal to reset your DNS and network stack

1. Open Terminal from Finder > Applications > Utilities.
2. Run this command: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
3. Enter your admin password and press Return.

Ok everyone, after a couple hours on the phone with Apple Support, the issue is.....FIXED(???)!?

After several steps involving "sudo diskutil resetUserPermissions / `id -u` " from terminal, "repairHomePermissions" from Recovery boot terminal, reinstalling Tahoe, rerunning resetUserPermissions because my entire user folder was inaccessible after reinstall (would not recommend), booting in safe mode, creating a new network location, uninstalling Windscribe, all of which did nothing...

We went System Settings > General > AirDrop & Handoff, and switched Handoff off, AirDrop to No One, and AirPlay Receiver off, my network connection completely stabilized. Even after switching all of those back on, my network has SO FAR remained completely stable.

I'm testing my network by running a continuous terminal ping to my router IP, which previously was showing an average around 3ms and then a spike every few seconds up around 50-100ms; now it is hovering steady around 3ms. My remote gaming Shadow PC which was previously getting choppy video/audio is now working smoothly.

So at this point it's unknown exactly which feature was the problem between Handoff/AirDrop/AirPlay, but it seems like something in one of those configurations that got corrupted in the update was reset/recreated by switching them off and on. I'd recommend everyone give that a shot and write back if it works for you, I hope so! And I'll let you know if the problem comes back.

I had the same issue on my MacBook Pro M3. My Mac installed the Tahoe 26.1 update automatically. I quickly noticed a network problem: the connection was extremely slow, and I got a few crashes with ERR_TIMED_OUT and ERR_NAME_NOT_RESOLVED.

I then updated to Tahoe 26.2, but with no success. I had the same errors after rebooting. I decided to reinstall Tahoe 26.2 from the boot menu without erasing my data. That solution worked for a few hours. I investigated and saw that my Mac would switch from 5 GHz to 2.4 GHz, and then the connection would crash. My Wi-Fi was using band steering, so I didn’t have separate 5 GHz and 2.4 GHz networks. I created two separate SSIDs (one for 2.4 GHz and one for 5 GHz), and since then I haven’t had any issues.

I will keep you updated if it crash again.

Hope this help

allen546 wrote:

Update: I reran tests on the 2.4GHz spectrum and the network is much, much more stable, even thought the speed isn't as fast as 5GHz. Of course by stable I meant stable in terms of Tx Rate (>= 40) and MCS index (Only once dropped to 3 and the rest is all >= 4)

--- 192.168.0.1 ping statistics ---

1000 packets transmitted, 979 packets received, 2% packet loss

round-trip min/avg/max/stddev = 1.778/92.278/2116.995/244.039 ms

Those ping numbers look pretty bad, almost unworkable. 2% packet loss is bad. The ping times ... average = 92 ms (that's very poor), max = 2117 ms (very poor, that's 2 seconds), and stddev = 244 ms, also unstable. Are these numbers from your network when it is working well? Because I would then wonder about the router or the network setup, or maybe an irregular internet provider? Or router or modem have incompatibilities with Tahoe?

Maybe next step is run Etrecheck and post its report here. Walk into an Apple Store and there are scores of Macs there on Tahoe running Wifi, including the new ones on display as well as user computers brought in, I have never seen such poor performance. I think you (and maybe the others with this issue) are being undermined by something installed that doesn't work right with Tahoe. That would not be your fault, but rather the developer's fault, but you want to identify and isolate the cause.

After following a strange recommendation in this thread, I created a new test Mac user account, and after a few hours of testing, performance seems to be...perfect??

Can some others test this so we can see if it's a viable solution?

If so.....

1. what the he¬¬
2. maybe something in the user account gets screwed up in the update? maybe it can be found/fixed/cleared?
3. can a user account be duplicated? or is there some other easy way to completely migrate everything from one account to another on the same computer? i doubt it...probably would need to be backed up, wiped, brought back w/ Migration Assistant, but would that bring the corruption with it?

I also actually tried testing using fast user switching, leaving my original/real account still logged in and "switching" to the test account, and it did NOT work, I had the problem on the test account as well. So apparently still having the original account open in the background was causing a problem.

You can try this. No guarantees it will work.

To reset network preferences on a Mac by deleting .plist files, disable Wi-Fi, open Finder, press Command+Shift+G, enter /Library/Preferences/SystemConfiguration/, and delete files like com.apple.airport.preferences.plist, NetworkInterfaces.plist, and preferences.plist to the Trash. After restarting the Mac, your system will regenerate these files with default settings. 

Steps to Reset Network Preferences

1. Turn off Wi-Fi: Click the Wi-Fi icon in the menu bar and select Turn Wi-Fi Off. 
2. Open Finder: Click the Finder icon in your Dock. 
3. Use "Go to Folder": Press Command+Shift+G to open the "Go to Folder" dialog box. 
4. Enter the Path: Type or paste /Library/Preferences/SystemConfiguration/ into the box and press Go. 
5. Delete .plist Files: Locate the following files in the SystemConfiguration folder and drag them to the Trash: 

• • com.apple.airport.preferences.plist
  • com.apple.network.identification.plist (if present)
  • com.apple.wifi.message-tracer.plist (if present)
  • NetworkInterfaces.plist
  • preferences.plist

1. Empty the Trash: Right-click on the Trash icon in the Dock and select Empty Trash. 
2. Restart Your Mac: Go to the Apple menu and select Restart. 
3. Re-enable Wi-Fi: After your Mac restarts, turn your Wi-Fi back on from the menu bar. Your Mac will automatically create new default .plist files, and you'll be able to reconnect to your network. 

This is really nuts that the manual IP seems to be the fix. After replacing routers, modems, trying every Wifi frequency, channel, clearing out all wifi preferences, moving my router around the house, this SEEMS to be the only thing that's fixed it, that is, assuming it holds. For it to work I had to use "DHCP with manual address" and also assign the IP from my TPLink router DHCP Reservation settings. Only doing it on the Mac side had no effect, while using the full "Manually" setting resulted in no internet access.

Update: I reran tests on the 2.4GHz spectrum and the network is much, much more stable, even thought the speed isn't as fast as 5GHz. Of course by stable I meant stable in terms of Tx Rate (>= 40) and MCS index (Only once dropped to 3 and the rest is all >= 4)

--- 192.168.0.1 ping statistics ---
1000 packets transmitted, 979 packets received, 2% packet loss
round-trip min/avg/max/stddev = 1.778/92.278/2116.995/244.039 ms

2019 Intel mac here, running Tahoe.

Wi-fi to home router is broken after update but works on many other wireless networks. At home, I have resorted to manually assigning my IP address which solves the issue but indicates there's something wrong with the DHCP process. We have about 12 other devices running just fine on this 5Ghz Wifi network. This is the first time owning a Mac that I've had such an awful experience with a new update. Restarting router, deleting .plist files, removing networks, did not solve the issue—just a straight up manual setting of my IP. Wild.

This is intriguing, and baffling, at the same time. I'm going to give this a try as soon as I post this, but my assumption is the same as yours--"something" on our current user account is cause this. So, what happens if you take your new test user account and simply sign into your Apple Account (via System Settings)? Does the old behavior return in that case?

You probably see where I'm headed with this. If a vanilla/virgin user account does not exhibit the problem, but the same account immediately has the problem after nothing more than signing back into your Apple Account, then the problem is going to follow us even if we migrated to a new Mac user.

This is starting to remind me of an issue I chased years ago on my Mac where wireless would go wonky on a predictable cadence. Actually, this happened in two different cases for me. One case was ultimately due to awdl0 (ugggghhhh.... don't get me started on this one.) and the second was due to a Location Service running a background wifi scan. The channel scans hurt--anything causing our wireless radios to "pause" and switch channels is going to be noticeable at some point.

Anyway, talk is cheap. I'm going to try some things on this path you paved and see where it goes... thanks!

@alirezazgr and @ffjxc -- Maybe try the macOS 26.2 public RC? I upgraded to it last evening because of hoping it would help with some of the same wireless woes you've described here. I figured it couldn't make anything worse (although I know that is often not true).

I seem to be having a better wireless experience at this point on it. Maybe you'll have the same luck?

Is iCloud Private Relay disabled?

Ok, little bit more data:

• updated to 26.2
• repeated the whole network files/settings reset process such as this (and left Location Services disabled for testing)
• ran Disk Utility First Aid from recovery partition
• logged in w/ my Apple Account on my new test user

Behavior is exactly the same: bad on my current user, perfect on my test user.

I hear where you're coming from on the hardware problem angle. Hardware can, and does, fail at times.

But, I have been running the 26.2 betas for a bit and now the RC/GA. It didn't fix the wireless issues for me, though others' experiences could be different I suppose. I can tell you with confidence this issue presents itself across multiple Apple devices in my home, all of which are running version 26 of their respective OS flavor (iPads, iPhones, MacBooks). It would be a pretty wild assumption that half-dozen+ Apple devices in my house all developed a hardware issue at the same time.

I'm going to try @Shade of Blue's suggestion of trying a new user account. May not be part of any solution in the end, but it feels like something worth trying.