I'm moving this post to the Sandbox forum.
Have you a current running Sandbox reservation that has provided VPN credentials to this lab? What do you mean by "connect to the production ASAs no problem"?
I have checked Anyconnect access to that lab and it works fine.
I did have a reservation at the time I experienced the issue, and I had been sent an email with credentials.
"connection to production ASA no problem", I have a customer that uses AnyConnect VPN on an ASA and I was able to connect to that without issue (thereby ruling out client side issues like firewall, host based firewall, etc).
At any rate, the next morning I tried connecting again to devnetsb12 and this time it worked, but my credentials failed (probably because it was outside of my reservation time frame). Looks like devnetsb12 was experiencing an issue that night for whatever reason.
All a moot point now as my window has come and gone, will have to try another reservation sometime next week.
Next time you have a running reservation you should be able to connect without issue. I am not aware of any problem with that lab currently. If you experience the same issue, please respond to this thread.
Apologies for the inconvenience.
Anybody else have issues connecting to devnetsb12? Tried AnyConnect client on Windows 7 and Windows 10 machines, cannot connect to devnetsb12 but can connect to production ASA's no problem. Packet capture shows client send client certificate, but never receives a server certificate back so the connection times out. Error message in AnyConnect is "Connection attempt has timed out. Please verify internet connectivity". Again though, via packet capture I see three way handshake and then client certificate being passed with TLS 1.2 being preferred, but no server certificate sent back thus timeout.