According https://wiki.mikrotik.com/wiki/Manual:Switch_Chip_Features#Introduction MT7621 based devices (hEX, hEX S) don’t have VLAN table in switch chip, but MT7621 datasheet http://www.trolink.cn/UploadFiles/Product/20160419152925_77763.pdf indicates: “Supports 4K VLAN entries”. Also https://wiki.mikrotik.com/wiki/Manual:Basic_VLAN_switching#Other_devices_with_built-in_switch_chip recommends configure switch chip VLAN features for hEX.
So it’s error in description MT7621’s features in wiki or Mikrotik didn’t use available VLAN table?
I don’t have hEX S for now, but it fits very good for my project, of course having VLAN table feature.