I try to replace pfsense with OPNsense.
As router I use mac mini with single port. Both WAN interfaces and all home subnets separated in vlans on cisco. My provider require mac adress, to test opnsense I just get PC with single port and do the same vlan interfaces. I able to get wrong ip adress on interfaces, able to ping ip on vlan interfaces in cisco. To test internet I override MAC adress on WAN interfaces and WAN interface stop work after that. From one provider I able to get correct ip adress but not ablr toping gateway, from second provider I not able to get ip adress. Changing mac on LAN vlans (for test) lead to the same behavior - interface with overrided MAC work on very strange way - DHCP server provide ip for clients but ping didn't work. Revert mac to original - all work as expected but not WAN because I need different MAC on WAN.
Do we have way to override mac on vlan interface?
It looks like chahge mac address on VLAN woirk only in promiscuous mode enabled. I didn't finish all tests but I see correct responses with tcpdump enabled on interface. But tcpdump emable promiscuous mode.
Interface has "promiscuous mode" in settings may be it can help resolve issue with custom MAC address in vlan interface.
If you leave the parent interface MAC at default promisc mode is required for its VLAN devices with a different MAC address, yes.
Cheers,
Franco