Off site Wifi proxy

[Dogfish]

Hi,

I am trying to get wifi users to go through my local proxy. These users are at an offsite location. Local wifi users are using wpad so they work fine. The primary purpose is to block https sites like facebook, etc.

I have 4 overseas office sites with standard isp routers and wifi. I have setup openvpn on each lan connected pc and forced each machine to use my proxy local ip via openvpn. Squidguard blocks certain sites. This is working well for fixed lan connected PC's

The problem that I have is that people that connect at the remote sites to the wifi with their phones, laptops and ipads  do not have openvpn or proxy setup.

I think the solution I need is to have the vpn and proxy setup on the router level so that all data is sent through my proxy.

Can anyone give me some direction on this.

thanks.
DF