Firewalls are a common cause of failed Connection Tests, below you will find the documentation to send their IT Department in order to unblock our traffic.
Instructions
Confirm user has camera and microphone connected. If a user does not have a microphone, they will fail the connection test (Pre-call Test).
If a user does have a microphone and still fails, this indicates possibly a slow network condition or a firewall issue.
Make sure the user is not connected with a VPN or any type of Remote connection.
Email user firewall information or send directly to the user’s IT Department to have the site whitelisted.
Firewall information listed below.