Which firewall ports are required to be open for a successful outbound connection when configuring...

The firewall ports that are required to be open for a successful outbound connection when configuring integrated secure connect gateway are 443 and 8443. Integrated secure connect gateway is a feature that enables secure remote access to the Dell Unity system through the Unisphere Central web portal. It requires an outbound connection from the Dell Unity system to the Unisphere Central server over the internet. Port 443 is used for HTTPS communication and port 8443 is used for WebSocket communication.

References: [Dell EMC Unity: Unisphere Overview], [Dell EMC Unity: Integrated Secure Connect Gateway]