You may face the CIMS server is offline. You have tested the network and the interface appears to be fine. Also, you don't see any problems with the hardware.
Xen bridge may cause the application server is not able to reach the gateway, although the database server is able to reach the network. This can be fixed with the restart of the host machine, which will restart the CIMS system and test server. Please reach out to the Support team and confirm explicitly that you allow restarting the host machine. Please note that it may take some time as it may force the disk check.
Please note that very often when the customers cannot access CIMS the agents are unable to reproduce the issue since the CIMS front-end is loading fine without any issues from our VPN. See more details about why this is happening in the internal article written for the Fat Face customer as an example.
The full process of restarting the host server and shutting down all of the VMs that are running on the host server is described in the internal article.
After you complete the reboot, ping the gateway from the application server to verify the connection.
After the support agent will complete the reboot and get back to you, please check and confirm that CIMS is working normally on your end.