Discovery Home Subnet Discovery does not run 'Network Routing Device - Light' pattern against the next hop Routers/L3 Switches of the starting routers, and it should.
This leads to failing to discover the next hop routers/L3 switches in the chain.
'Network Routing Device - Light' pattern will run only against the starting router and it will not be triggered against the discovered next hops of the starting router 'MID server default gateway'.
'Network Routing Device - Light' pattern should be triggered by Subnet Discovery - On Target Discovery Success - Post Sensor Script against the identified next hops.
This problem is currently under review. You can contact ServiceNow Technical Support or subscribe to this Known Error article by clicking the Subscribe button at the top right of this form to be notified when more information will become available.
The routers could be added manually to the Subnet Discovery configuration. You can query a list of the dscy_route_next_hop table for the first router, where dest_ip_network is "0.0.0.0/0" to find the routers.