OpenVPN: Route all traffic through server from client config

I am afraid you will need to do some reading on IP routing. A good starting point could be here. Now to your specific problem: you need to replace the "def1" with the address of your IP tunnel, so that all traffic is by default routed into the tunnel.

However, please note that this will route really ALL traffic through the tunnel. If you want to only route traffic for specific target networks through the tunnel you will need lines similar to this:

push "route 192.168.10.0 255.255.255.0"

In this example, 192.168.10.0 stands for the network address of the subnet, and 255.255.255.0 stands for the subnet mask. If you don't know what these terms mean, then you should start reading.

For reference, the relevant section of the HOWTO is here, though I suspect you've followed that.

The first thing I'd try is to remove the 'local', that is the command should be

push "redirect-gateway def1"

and not

push "redirect-gateway local def1"

The local flag only works if all of your clients are on the same subnet.

A couple of other things to be aware of are that DNS traffic is routed through the vpn so you won't be able to resolve addresses unless you've dealt with that. DHCP can also get forwarded though it doesn't look like that should happen in your case as you're using a routed not a bridged VPN, but might be worth checking anyway.