This was working for me yesterday, and is also working on my colleagues machine but mine is failing all of a sudden. Tried adding allowing ports in firewall as well. This is stuck indefinetly.
What are you using for authentication? If using certificate, I would verify the certificate is not expired.
Also I would review the client vpn logs on the users workstation directly
This should help https://docs.aws.amazon.com/vpn/latest/clientvpn-user/windows-troubleshooting.html
Also I would very no GPO changes were made company wide that limited privileges for network adaptors locally on your workstations