Hello,
The /32 mask shouldn't matter, unless you need communication between the Dialup user machines themselves. The Firewall injects a tunnel route to client machines once the VPN IS connected.
For example - in the How-To you have shared, every client will get a /24 route for the 10.1.2.0 network once the tunnel is established.
If you want the clients to tunnel everything, you may want to modify this to 0.0.0.0/0, but that may also have adverse effects.