SSL VPN UTM dd-wrt partially working...

Hey,

I have a problem.
I've Connected my home UTM with a DD-WRT owned by my brother. (SSL VPN)

I have the address range:
192.168.0.1 - 192.168.3.254
subnet 255.255.252.0

My brother has the address range
192.168.4.1 - 192.168.4.254
subnet 255.255.255.0

I followed the following instructions:
Insatiable Ramblings | Astaro Site to Site VPN with DD-WRT

This does work, partially ... : (

My brother is coming into my network, but I can not get into his.

I'm assuming the DD-WRT has be set the routes correctly.
My UTM does not...

How do I fix this?

I thank you,
Ciao