The route translates to 172.16.0.0/12 via 172.25.73.161
. So you can configure it in NM like this:
nmcli con modify "connection name" ipv4.routes "172.16.0.0/12 172.25.73.161"
Or use nm-connection-editor
– under "IPv4 Settings" / "Routes", add 172.16.0.0
with netmask 255.240.0.0
, gateway 172.25.73.161
, and the default metric.
To add the route just temporarily, use:
ip route add 172.16.0.0/12 via 172.25.73.161
Also, your requirements contradict themselves.
172.16.0.0 with netmask 255.240.0.0 is not the same thing as "172.*.*.*" – the netmask only covers addresses from 172.16.0.0 to 172.31.255.255.