Now since the RBLtAP-2HnD board actually doesn’t make use of the internal LAN switch of the MT7621A, it seems plausible for me that vlan may work, but I prefer having confirmation from Mikrotik before purchasing one.
The device performance depends on the way VLANs are configured:
handful of devices have full HW offload supported even if VLANs are configured in the new bridge vlan-filtering way.
This is the case for CRS3xx devices
majority of devices, which feature switch chips, can have VLANs configured in two distinct ways. If they are configured the old way, using switch-chip specific commands, then they support HW offload for packets flowing between ports of the same switch chip (the rest is handled by CPU). If these devices are configured the new way, then all traffic is handled by CPU which can severely affect the device performance.
This is the case for most RB devices with switch-chips except devices with Mediatek or Realtek switch-chips.
handful of devices which don’t feature switch chips, have to do VLANs by CPU. The performance hit (compared to untagged config) is neglectable as they move packets between interfaces through CPU anyway.
This includes all CCR devices (except an old 1036).