The exact URL depends on your specific Firebox configuration :
: Users enter the URL in a web browser and authenticate using their Firebox-DB, RADIUS, or AuthPoint (MFA) credentials. Watchguard Vpn Url
: If other features like the Access Portal or Branch Office VPN (BOVPN) over TLS are active, they may share the same port (usually 443), with specific precedence rules governing which feature "owns" the port. The exact URL depends on your specific Firebox