Use the client to specify the cidr network segment for the route in the local_routes parameter. The format is as follows, one per line.
192.168.11.1/24
172.18.0.0/16
100.100.100.100/32
1.0.0.1-1.0.0.25
25.25.33.9-120.22.33.11
10.10.10.10
11.11.11.11