Thanks for your help, i tried to install the VPN client but seems that i need some extra access permissions. Don't understand why that might be needed for a client software.  

I tried to connect by VPN, i have paloalto client and it is not reachable (same issue as the DNS) --> check below screenshotVPN URL: devnetsandbox-usw1-reservation.cisco.com:20290  

i tried an online checker and couldn't find hq-cucm-pub.abc.inc through the DNS 10.10.20.100 (check below screenshot) .sounds like the DNS is not reachable. i'm located in Egypt  

Thanks for helping, here is my detailsEnvironment name: "Unified Contact Center Express 12.5-20240827T09105090"Environment URL: https://devnetsandbox.cisco.com/DevNet/environments/g8KL020hpm4J/simplified