#201 local_net
#202 main_inet
#203 backup_inet
network:
  ethernets:
    #201 local_net
    ens160:
      dhcp4: no
      addresses:
        - 192.168.150.170/24
        - 192.168.150.171/24
    #203 backup_inet
    ens192:
      dhcp4: no
      addresses:
        - 89.89.89.174/28
      #routes:
        #- to: default
          #via: 89.89.89.161
          #table: 203
      #routing-policy:
    #202 main_net
    ens224:
      dhcp4: no
      addresses:
        - 212.212.212.70/29
      #routes:
        #- to: default
          #via: 212.212.212.65
      #routes:
        #- to: default
          #via: 212.212.212.65
          #table: 202
      routing-policy:
        - from: 192.168.150.35
          to: 8.8.8.8
          table: 202
          priority: 90
        - from: 192.168.150.35
          to: 8.8.4.4
          table: 203
          priority: 100
        - from: 192.168.150.36
          table: 203
          priority: 110

routes: должен находиться под своим интерфейсом
например: ip route add default via 212.212.212.65 dev ens224 table main_inet
должен писаться в описании интерфейса ens224

routing-policy: не привязывается к интерфейсу и
может быть указан под другим интерфейсом

mcedit /etc/networkd-dispatcher/routable.d/10-add-routes.sh

#!/bin/bash
ip route flush table main_inet
ip route flush table backup_inet
ip route flush table local_net
ip route flush default

ip route add default via 212.212.212.65
ip route add default via 212.212.212.65 dev ens224 table main_inet
ip route add default via 89.89.89.161  dev ens192 table backup_inet
ip route add default via 192.168.150.100  dev ens160 table local_net