I am working on this very issue here. Since you’re bypassing the retail gateway, you’ll need to process 802.1P packets. Ultimately we need MikroTik to enable us to use VLAN id 0, and set the 802.1p bits on egress. For now, you can support the ingress like so:
# allow ingress packets with VLAN ID 0, to not get dropped
/interface ethernet switch port
set ether1 vlan-mode=fallback