hotspot behaving strangely

Greetings,
I have a hotspot config as such ;
gateway->MikrotikHotSpot->ethernet-> WDS wireless bridge network (three ubiq radios).
Clients seem to connect properly to any of the WDS radios and get DHCP addressing from the Tik and the login page is displayed properly, and the user may login.
However, there seems to be no DNS services available after the login, unless the user forces a reconnect to the WDS wireless network - after which everything is perfect.
Can anyone see what I’m missing here?

Many thanks