Interestingly just tried the following:
- provision node via "vagrant up"
- suspended node
- Started up node again and see vmnet route entries re-added to host node
- I am able to connect to instane again over SSH
So issue appears to be vmnet routes to NAT subnet being dropped during first startup.
[Edit]
NAT routes are dropped after a time period on these failing machines. Lost connection again after above sequence because local routing was lost again.