Fixed: iMac Unable to Connect to Internet After Sequoia Update

Solutions

Solution 1:How to Delete and Re-add WiFi Service on macOS

•  Delete and Re-add WiFi Service>Go to System setting  Network.
• Right-click WiFi in the left panel and select Delete Service.
• Click the + button, select WiFi, then click Create to add it back

Solution 2: Disable Old VPN or Filters to Fix Connected but No Internet Issue on Macs

• Open System Preferences > Network.
• Click on VPN & Filters.
• Look for any VPN software or filters marked as Enabled.
• Change them to Disabled.
• Check if the issue is resolved.
•  After making these changes, restart your Mac.

Solution 3: Uninstall Antivirus, Cleanup Apps, or VPNs and Restart in Safe Mode

• If you're facing internet connection issues, it could be caused by antivirus software, cleanup apps, or VPNs that are interfering with your connection. 
• Uninstall any antivirus, cleanup apps, or VPN software.
• Restart your Mac in Safe Mode by holding Shift during startup.
• Once in Safe Mode, restart your Mac normally.

Solution 4: Check WiFi Details and Adjust Settings
If you're having trouble with your internet connection, try adjusting the WiFi settings on your Mac:

• Go to System Preferences > Network.
• Select WiFi from the list of network connections.
• Click on Details or Advanced (depending on your macOS version).
• Look for options like Fixed and Off in the settings.
• Try switching these settings to Fixed or Off, depending on what options are available.

The issue of iMacs being unable to connect to the internet after the Sequoia update likely stems from a software or driver conflict that prevents the device from establishing a proper network connection. This problem could manifest in various ways, such as no Wi-Fi access, Ethernet connectivity issues, or network settings being reset.