Determine the configured DNS server by viewing the WAN interface in the portal.
Use dig @<DNS IP> gatekeeper.trustgrid.io +short to confirm you get a response from each of your DNS servers. E.g. if the appliance is configured to use 8.8.8.8 and 1.1.1.1 use the commands dig @8.8.8.8 gatekeeper.trustgrid.io +short and dig @1.1.1.1 gatekeeper.trustgrid.io +short
If the above does not resolve, make sure any firewall or access control list between the node and the WAN interface IP allows the IP to make DNS connections to the configured DNS servers on TCP & UDP port 53. If it successfully resolves, continue to the next step.
Confirm Network connectivity to the rest api endpoint with the command
nc -vz gatekeeper.trustgrid.io 8443
If this succeeds as shown in this image proceed to the next troubleshooting step.