@ldiciolla as xcp-ng version 7.x you must add 4 extra in the mtu 1500 cause the nic in xen has no 802.1q vlan driver due that the max vlan 4094 is done like
1024 2048 4096 4096 is how memory is allocated but the mtu 1500 is the tcp mac window max trans (m)utex just add 4 in the mtu and there the vlan number will be stored (in v8)this is covered , pfsense runs in a vm so don't allocate vlan(s in vlan(s on the gen1 hypervisor , buy a switch vlan802.1q built there your nic vlan in and deliver pfsense simple lan interfaces reason is the nic must also be vlan capavle, by using a switch this is covered and on one realtek i ran wan lan1,2,3,4,5,6
always tag the port the 802.1q has nothing to do with the ARP MAC thats in 802.1ad
vlan 4096 tag means all vlans and start by id 4 due 1-3 is are used for LAG not like LACP or LACP.802.a3d ,