so, i have enp420 & tun0. when tun0 comes up, route are not properly update for tun0 routing. i think...
default via 10.0.0.1 dev enp4s0 proto dhcp metric 100
10.0.0.0/24 via 10.0.0.1 dev enp4s0 proto static metric 2
10.0.0.0/24 dev enp4s0 proto kernel scope link src 10.0.0.101 metric 100
10.8.0.0/24 dev tun0 proto kernel scope link src 10.8.0.1
10.8.1.0/24 via 10.8.0.2 dev tun0
10.8.2.0/24 via 10.8.0.2 dev tun0
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
looks like maybe some NM policy is broke?
does NM create proper route for your vpn on NM restart?