Network routes?

[Knute Johnson]

I have an Xubuntu 23.04 desktop with two NICs.  One is my local network 
and the other comes from a hardware VPN device.  That NIC gets an 
address from DHCP in the device.  That network is 172.0.10.0/24 with a 
router at 172.0.10.1 to get to the rest of that network.  I'm running 
NetworkManager and when I go to edit that connection and put in a route 
for the networks that are reachable through the 172.0.10.1 router it 
doesn't work.  If I put a route in on the command line:

ip route add 172.0.0.0/11 via 172.0.10.1 dev xxxx metric 1

I can now reach all of the devices on the network through the 172.0.10.1 
router.

Anybody know why it doesn't work if I try to set it up in NetworkManager?

-- 

Knute Johnson