No internet with WAN using Static, only with DHCP

[Yeff]

OPNsense "lab" router only connects to internet with OPNsense WAN on DHCP, won't connect when set to static.
IT kook here.
26.1 baremetal in my "learning lab" connected to internet via main router.
Main router port set to only 100.100.100.1/24.
OPNsense router will only connect to the internet when WAN on the OPNsense router is set to DHCP and not when set to say. 100.100.100.100.
If an OPNsense firewall rule is causing this, is there a way to see which rule is doing this?

Any suggestions why?

When I move the cable to a mac with static ip on the 100.100.100.1/24 subnet, it connects.

[Patrick M. Hausen]

If you configure statically you need to also manually add the default gateway. System > Gateways. DHCP takes care of that.