I have TEC fiber that uses an ONT. When I connect an ancient Netgear router to the ONT it gets my Static IP address every time. When I connect the WAN port on OPNsense to the ONT I get a gateway address. I can't access any local servers from the web, and I haven't seen this addressed in countless searches. The WAN is configured PPPOE, and it connects fine. The only problem is that it doesn't get my static IP address.
What does "I get a gateway address" mean? What do you expect to see? What do you actually see?
Nothing on your LAN will be accessible from the internet unless you setup port forwarding for it.
Maybe the OP is looking at the Gateways widget on the dashboard. It displays the WAN gateway IP...
The WAN IP is visible in Interfaces > Overview.