unskilled wrote"push "route 192.168.20.1 255.255.255.0"
This should be:
push "route 192.168.20.0 255.255.255.0"
But that will not change the problem you are having not being able to connect.
You need to learn how DD-WRT firewall works.
Open the UDP port 1194 to the internet (but I do not use DD-WRT so I cannot help)