After updating my M3 Mac Pro to macOS Tahoe 26.0.1, I completely lost internet connectivity

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. 

Just a thought.

If you are running a VPN it could be interfering with your connection.

I'm at macOS 15.7.1 (24G231) Sequoia pre-26 update stage and experienced the "Cannot Connect to Server" message incessantly when trying to sign in to a newspaper subscription.

I decided to turn off my VPN (PIA) "Private Internet Access" and SHAZAM! — the problem disappeared instantly. I also decided to wipe my History and re-start my MBP M3Pro.

No problem. I then turned on PIA and the problem remained gone.

Whenever the message returns, I give it the "Turn off PIA" and all is well.

This has been the only difficulty I've experienced in six years of continuous PIA use. It has only occurred with recent iterations of macOS 15.x — so I'm inclined to blame the evolution of our macOS and continue to use the "PIA ON/OFF" workaround.

I'm also going to stay in my holding pattern before committing prematurely to the macOS 26 Tahoe update. It's a massive update, so I expect to be holding off until a comprehensive "ALL CLEAR" agreement is arrived at.

I hope this workaround with the VPN works for you, BSD.

You might have tried this but I have to ask, did you try "Forget This Network" in WiFi?

I've had the same experience, but seems to only be limited to WIFI, personal hotspot loads correctly. I believe if its anything like my phone on ios26 its the Private Wifi, if I switch it off and on again reboot, forget network it works temporarily but then stops again. Can't find a permanent fix, unfortunately it's a bit of a dance each time to get it working temporarily.

Don't know if this will help but I'll put up just in case.

If your Mac isn't connecting to the internet over Wi-Fi

The whole thing about Wifi is here

Connect to the internet with your Mac

Hopefully it isn't a VPN that causing the problem. On the iPhone VPN's cause nothing but trouble.

Hi, I've the same issue since I upgrade macOS 26.0.1 on my MacBook Pro M4 Pro. my Wifi disconnects every few minutes and especially when I use a lot the bandwidth for activity like big files download.

it is clearly a bug from 26.0.1, my wife on her old MacBook does not have any issue !

please Apple, fix it ASAP !

Having this issue on my MacBook Air M1 2020 running Sequoia 15.7.1. Have restarted modem, router and computer multiple times. Have deleted and re added the WiFi network multiple times. Have deleted the recommended plist files. Have cleared history and emptied cache in Safari. Even deleted my vpn. And tried turning off private browsing. Cannot reinstall Sequoia because the WiFi connection to my MacBook is too unstable, even sitting right in front of my router and modem. Hot Spot works, but I often have to restart my computer to get it to rejoin the hot spot. Safari is almost unusable. Chrome worked better for me last night. But I’ve stopped trying to do most things on my laptop. It’s incredibly frustrating.

Have you tried a different browser, such a Chrome, Brave, Opera, etc, etc?

It might be that new MacBooks also have another band than those of us with older MacBooks don't and that you have to enable it on the router (if it has it) to the 6 GHz.

I tried many actions including rebooting the router, rebooting my Mac, forgetting this SSID and reconnect, try another Wifi and there is definitively an issue !

It appears only after the update 26.0.1 and worked perfectly before (26.0.0 and before)

@apple please fix it.

Happy to help identifying the root cause by proving more info...

I’m having the same issue, and have tried everything so far with no luck. And I can’t even change de MacOS version back because I can’t get it to connect to the internet with any wifi. This is terrible. Totally regret having updated to Tahoe (I went from Sequoia directly to Tahoe 26.0.1)

How to revert to Sequioa from Tahoe