Alright 
Since we already have subnets starting with 10 and 192, I use 172 
That not solve my problem, but I manage to get working using (again) the routing table, now I use the same gateway of the RED (not the red has gateway, just the same gateway that subnet uses). For example, if I have a petition from 10.20.90.0/24, instead of using 10.20.90.254, its gonna use 192.168.2.254… the problem? I can’t access to IPFire using 10.20.90.190, even when my computer is on the 10.20.90.0/24 network, but I can if I use the VPN 
But, at least, the client can start working with his server, that’s enough for now