I'm wondering how to let my wifi users onto the internet

But block LAN based traffic? (by LAN I mean wired connections)

How would I implement this, my model is a Vigor 2860ac

I can't see how to differentiate between LAN and WLAN in the settings?

EDIT: Found it, I created a couple of VLAN's, one with wired access, one without

Firewall filter did the rest