Isolate LAN on etherport?

Hi,

I have a rb2011 running as a router LAN (192.168.88.xx). On “ether10” i have a ubiquiti m2 that i want to isolate from LAN. This should only connect to WAN. This has a satic DHCP (192.168.88.253)
I have tried with config. #9 with no luck?
Config