Hello,
The issue has already been forwarded to the development team.
At the moment, you can check Network -> Interfaces section, where Main WAN is the highest online interface in the list.
It can also be derived from the routing table from Status -> Routes -> General routes section as a route with 0.0.0.0/0 Target and lowest metric.
SSH command:
will also provide you main WAN interface name.
Best regards,