DNS not resolving on wifi, but works fine on ethernet

One of my users has a Macbook 3,1 running 10.6.8. DNS lookups no longer work when she’s connected to the LAN via wifi. Lookups do work when connected via ethernet.

Both ping & nslookup fail on a wifi connection to the LAN. She cannot ping an external IP (8.8.8.8). She can ping other LAN nodes. No problems when on ethernet.

DHCP is working fine in both cases.

The AP is the same in both cases (it’s a wifi AP with four ethernet ports).

DNS still fails when connected to another LAN wifi AP.

DNS does resolve on wifi when she’s connected to my phone’s ‘mobile hotspot’. It apparently works fine on her home connection as well.

I don’t see anything useful, or even related, in the console log.

She has reinstalled 10.6.8 on top of the existing install.

The nut of the problem seems to be:

* Cannot resolve DNS on a LAN wifi connection

* Can resolve DNS on a LAN ethernet connection

* Can resolve DNS on other wifi connections

I’ve run into something similar in the past that turned out to be a MAC/IP binding issue on the router, which is why it didn’t work on wifi but did on ethernet. There’s no binding set for anyone on this router, though.

Anyone else run into something like this? I’m just about out of tricks on this one.