@Tedd404 @Virgo Thank you for your replies. It was late and it was a self-inflicted wound. I had unintentionally tagged the other ports with the default VLAN instead of only setting the uplink ports...

Hello community, This is my last hope before I package everyting up and send back to TP-Link (which I may end up doing anyway as their support is abysmal, see further down). This is my first...