After performing a bootstrap and the Symantec Endpoint Detection and Response appliance reboots, you have no network route and the default gateway is blank.
The interface eth0 or one of the static routes has an invalid netmask value of 255.255.255.255. This can happen if you set a static route for the IP 0.0.0.0.
You will need to re-run bootstrap to modify the network settings for eth0. If the misconfiguration was done for a static route, you can use the 'routeconfig' command to remove the incorrect static route.