Using PDANet and Adding Access Point Through Ethernet?

[Suika]

So I don't have an ISP and I've been using my phone to tether data to my desktop, and recently decided to share my data with siblings so they could game online at a decent latency. Currently, I've been running a VPN on my phone and tethering to my desktop, and configuring a static IP on my router to the VPN's provided IP. That works, but I was wanting something a little more plug and play so I don't need to leave my phone at home, or require a new line of service to dedicate a device to tether. Currently, this is my configured setup,

 

(The IP used is a previous one I remember)

 

and the problem I'm facing is that if I connect to the VPN, there's no guarantee I'm getting the same address and subnet, and my brothers are not even remotely as capable as I am to configure a new addressing scheme if the VPN doesn't spit out the same one. I've tried configuring the router as an access point instead, but I can't seem to get any settings that will keep devices online.

 

E: The router is some cheapo Netgear router I got from a friend. Can't remember what.

 

Basically, any suggestions as what I can do to make it a bit more plug and play, or how I could configure it as an access point instead of a router?