Is your Mac performing strange on Mac OS Sequoia 15.0? Here’s a possible solution.

Symptoms

Since upgrading to Sequoia, is your mac acting oddly?

  • Intermittent internet issues ? web pages don’t appear to load properly, but work if you refresh?
  • Video calls stutter more than usual, people can’t always hear you,
  • Web pages don’t appear to load properly, but work if you refresh.
  • You get “This site can’t provide a secure connection” error ERR_SSL_PROTOCOL_ERROR frequently in Chrome?
  • Downloads regularly failing ?

My laptop was useable (more or less) but I was starting to think my Mac had developed a fault or that my wifi was acting up. I suspected it might be ipv6 or wifi frequency issue (2.4 Ghz/5 Ghz) or some router transit issue, so started to work through possible problems – After an hour I found the root cause and a solution.

As of 20 September 2024 Microsoft Defender isn’t compatible with Mac OS Sequoia ! 1

In macOS Sequoia (version 15.0), if you have Network Protection enabled, you might see crashes of the network extension (NetExt). This will result in intermittent network connectivity issues for end users. We are recommending that customers who have Network Protection enabled in their organisation refrain from upgrading to Sequoia builds at this time.

How to work around and regain stability (or check if you have this issue).

Open settings.

Then > General > Login items & Extensions

Select Network Extensions, which will popup a box.

If you have Microsoft Defender installed it will show (as per above), swipe to Disable the Microsoft Defender. (Network extension) – note this doesn’t disable Microsoft Defender, just the network extension component.

Reboot and enjoy.

(If you don’t have Microsoft Defender here, then your issue might be something else – sorry!)

  1. https://learn.microsoft.com/en-us/defender-endpoint/mac-whatsnew ↩︎