I have a Slate AX and want to set up a VPN to route traffic back through my home network. We have this AirPort Extreme router that still works. Could I use this to setup my home server/exit node? If so, any idea how?
No, this router doesn’t support running a VPN server but you can buy a second GL.iNet router and use it to run the Wireguard server and plug into the Airport. Or run Tailscale on it. Or buy an AppleTV and run Tailscale exit node on that.
Sorry. That device has very limited advanced features so… no.
And with how old the firmware must be, I wouldn’t risk using it anyway on a network that is connected to the internet
If you need a VPN serveron the cheap, you could simply run a small VM with WireGuard or OpenVPN, or even better, a Docker container
The last firmware update was version 7.9.1 which came out in 2019.
That’s 5 years without any major security updates.
Even if the device still works, you’re going to be putting your network at risk by continuing to use a discontinued device.
Just call it a loss at this point and buy a newer router. Most recent routers have some type of VPN server software preinstalled and are easily configurable. I personally use ASUS ZENWiFi routers which can do what you want out of the box.