Just cracked it today :)
This article was super handy: https://www.dd-wrt.com/wiki/index.php/Switched_Ports
I had to SSH in and do this:
nvram set vlan10ports="0t 5u"
nvram set port5vlans="10"
nvram set vlan10hwname="et0"
And we're winning. Thanks for the help everyone!
Heck of a way around it, I was avoiding recommending shell as to not throw out of depth!
nicely done, how is performance looking?
Wow I was scratching my head with this yesterday! I'm going to try this later. Thank you.