They don’t make these anymore. But firmware upgrades are still available and maintained by Apple.
Apple Airport A1521 Extreme A1392 Express Wireless Extender Base Stations Router Bundle. Both units updated with the latest firmware. 7.8.1 (Express) / 7.9.1 (Extreme).
You can manage these devices using the AirPort Utility for macOS, iOS and Microsoft Windows.
You can also remotely manage them securely over SSH tunnels. I can show you how.
This combo is for the road warrior and those staying on hotels/motels. Take your private WiFi network anywhere. Retain your IP addressing the same way. Just update the Express to connect to a new WiFi hotspot and let the Extreme handle your devices.
Express can also be used to add wireless functionality (via Ethernet port) to any iMac G5/G4 sitting around your basement.
1GB secure WebDAV online storage space (https://danskoya.com/yourname/)