WAN interface gets public IP but cannot route to internet

[isfn]

Opnsense behind ISP router/ONT in bridge mode.
WAN interface (PPPoE) acquires public IP from ISP.
I cannot ping any public IP from the Opnsense box.
What could I be missing?

[pp]

I had to check System->Gateways->Single->WAN_DHCP->Upstream Gateway manually before I could connect outbound (maybe disable / enable gateway afterwards).