My WiFi connection says “weak security” how can I update my AirPort Extreme router?

Your AirPort Extreme should support WPA2, which will be sufficient to address the "weak security" message. To do so:

1. Open Airport Utility (it's under the Utilities folder in your Applications folder)
2. Double-click the AirPort image
3. Click Edit
4. Click the Wireless tab
5. Under Wireless Security, select WPA2 Personal

Even the "most recent" AirPort Extreme was designed more than 8 years ago, so the hardware is not going to be able handle newer WiFi security protocols like WPA3 or use 802.11ax, also known as WiFi 6.

The best that you can do security wise on an AirPort router is use the WPA 2 Personal wireless security setting.

Your AirPort Extreme should support WPA2, which will be sufficient to address the "weak security" message.

Not quite when the "weak security" message on an iPhone or iPad (connected to a WPA2 Personal network) links to an Apple document that says to use WPA3 for better security or WPA2/WPA3 Transitional for compatibility with older devices.

But WPA2 might be good enough for most folks for another year or two though.