New Mac update causing disconnection from wifi needing manual connection.

MacBook Air keeps disconnecting from Wi-Fi after macOS 27.0.1 update

Since the problem started after updating to macOS 27 Golden Gate 27.0.1, it is possible that the update affected your network settings or introduced a software compatibility issue.

Let us work through these troubleshooting steps, starting with the simplest.

A. Restart your Mac and router

1. Save your work and restart your MacBook Air.
2. Unplug your Wi-Fi router.
3. Wait 30 seconds, then reconnect it.
4. Allow the router a few minutes to restart.
5. Reconnect your Mac and check whether the connection remains stable.

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

B. Check your Wi-Fi settings

1. Open Apple menu > System Settings > Wi-Fi.
2. Find your usual network and click Details.
3. Make sure Automatically join this network is enabled.
4. Click Done and test your connection.

Apple guide: Wi-Fi settings on Mac

C. Forget and reconnect to your Wi-Fi network

Saved network settings can sometimes become corrupted or outdated.

1. Open System Settings > Wi-Fi.
2. Click Details beside your home network.
3. Select Forget This Network, if available.
4. Restart your Mac.
5. Select your Wi-Fi network and enter your password.
6. Ensure Automatically join this network is enabled.

Make sure you know your Wi-Fi password before forgetting the network.

D. Renew your DHCP lease

This asks your router to assign your Mac a fresh IP address.

1. Open System Settings > Network > Wi-Fi.
2. Click Details > TCP/IP.
3. Select Renew DHCP Lease.
4. Click OK or Done and restart your Mac.

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

E. Check VPN and security software

If you use a VPN, antivirus, firewall or other network security software, temporarily disconnect your VPN and check whether third-party network filters are interfering.

Restart your Mac and test Wi-Fi. If the problem disappears, check for software updates compatible with macOS 27. Restore your normal security settings after testing.

Apple guide: Check VPN and third-party security software

F. Check for macOS updates

Apple may have released additional fixes since macOS 27.0.1.

1. Open System Settings > General > Software Update.
2. Check for available updates.
3. Install any newer version if available.

Make sure you have a current backup before updating.

G. Test another Wi-Fi network

Connect your MacBook Air to another network, such as a trusted mobile hotspot.

• Disconnects on every network: macOS, your Mac's network settings or hardware may be responsible.

• Works on another network: Your home router or its compatibility with macOS may be the issue.

• Other devices also disconnect: The router or internet service provider may be responsible.

If the problem only occurs at home, check for router firmware updates.

Apple guide: Recommended Wi-Fi router settings

H. Check Private Wi-Fi Address

1. Open System Settings > Wi-Fi.
2. Click Details beside your home network.
3. Find Private Wi-Fi Address.
4. If set to Rotating, try Fixed, if available.

Reconnect and monitor the connection. This is a diagnostic test, not a guaranteed fix. Restore the original setting if it makes no difference.

I. Run Wireless Diagnostics

Your Mac includes a built-in tool to investigate wireless problems.

1. Hold down the Option (⌥) key.
2. While holding it, click the Wi-Fi icon in the menu bar.
3. Select Open Wireless Diagnostics.
4. Follow the on-screen instructions.

Apple guide: Use Wireless Diagnostics on your Mac

J. Test in Safe Mode

Safe Mode helps determine whether third-party applications or background software are causing the problem.

If Wi-Fi works normally in Safe Mode but disconnects during normal startup, a third-party application, login item or network extension could be responsible.

Restart your Mac normally to exit Safe Mode.

Apple guide: Start up your Mac in Safe Mode

K. Contact Apple Support

If none of these steps resolves the problem, contact Apple Support.

Explain that the disconnections began immediately after updating to macOS 27 Golden Gate 27.0.1 and that your MacBook Air now requires manual reconnection.

Ask Apple to investigate possible macOS Wi-Fi bugs, network configuration problems, router compatibility and available software fixes.

I would not recommend reinstalling macOS or deleting system network configuration files just yet.

There are several simpler troubleshooting options worth trying first.

In System Settings > Wi-Fi, click Details beside your network and check that Automatically join this network is enabled. If it already is, run Wireless Diagnostics by holding Option while clicking the Wi-Fi menu and choosing Open Wireless Diagnostics. Also test another Wi-Fi network or a phone hotspot to see whether the disconnections are specific to your router.