If you cannot get the DGN1000 working and are sure setup is identical, then you can use the 1000 to provide wireless off of the existing Sky router.
To do this you are basically converting the DGN1000 into a wireless access point (had advantage you can also site it to provide best coverage, rather than just next to a phone socket).
1. Connect to the DGN1000 to a computer using an ethernet cable
2. Ensure that this is the only thing connected via Ethernet or wireless to the DGN1000
3. In its web interface, disable the DHCP server
4. If the IP address of the DGN1000 is the same as the Sky router, then change the default LAN IP address on the DGN1000 to something different e.g. 192.168.1.200 (write this underneath the router as you will forget it)
5. Connect the DGN1000 to the Sky router, i.e. ethernet cable between a LAN port on both routers.
6. the wireless will continue to work, and IP settings will be handed out by the Sky router
7. If you need to change any wireless settings then goto http://192.168.1.200 (or IP you used) and the DGN1000's web interface will be available