I get this from time to time, even though I access it the same way. I just requested a reservation and got the email that Your Cisco Devnet Sandbox is Ready. I tried accessing it at devnetsandbox-us-sjc.cisco.com:20171, and get "VPN service unavailable; reason: No assigned address"
I see many topics like this with no real solution. One possible reason I can think of is that the DHCP address scope is exhausted.. thus, there is no available address. But I'm just speculating. Any ideas?
This happens to me from time to time. Once, I just cancelled the reservation, created a new one, and it worked fine.