Multi-WAN: can't ping gateway IP (with solution)

[Bren]

Hello! This took a long time to figure out so I wanted to post a solution here for anyone using multi-WAN in the future who hits the same issue. When using the instructions to set up multi-WAN (https://docs.opnsense.org/manual/how-tos/multiwan.html) by default you won't be able to ping your gateway IP. There was one post here about this years ago without a solution but I can't for the life of me find it.

Also, when you traceroute to your gateway IP, it'll get routed outside the firewall which at first is very concerning!

The hint to the solution is here: https://docs.opnsense.org/manual/how-tos/multiwan.html#step-5-add-allow-rule-for-dns-traffic. Instead of just allowing DNS, I allowed any port / protocol from my internal network. This allows DNS, ping, etc. Traceroute doesn't fully work but it doesn't route outside the network. Otherwise everything works as expected now.