Default [Q] My DNS is borked

I have a Lumia 800 in the UK.I used it in Indonesia with a local (Telkmosel) SIM. Now it is running on the UK SIM again (for six months).

I have it connected to my LAN and a local DNS entry on my LAN.

However for DNS it seems like my phone is using some external IP, and I don't know how to change it.

Example:

* add DNS entry for qil2.com (made up domain name, doesn't exist) to my local DNS server (192.168.0.10) to point at a local server (also 192.168.0.10)
* browse to qil2.com on my local PC - brings up local server as I intended
* go to phone, disabled mobile radio, enable WIFI, connect to my WIFI, verify gateway (192.168.0.1) and DNS (192.168.0.10), browse to qil2.com - goes to mercusuar.info/m.block?url=qil2.com&q=320 - an Indonesian website from Telkomsel.

Obviously it picked this up in Indonesia. How do I turn it off?