On this D-LINK support page:

http://www.dlink.co.uk/?go=gNTyP9CnptFMIC4AStFCF834mptYIe1STtvhLPG3yV3oUY98 g6ltbNlwaaRp6TotFj2onGQTo4oERpqmnfyia18TuO/aZ4K1HtG0

It instructs:

Step 1) Login to router, on the address http://192.168.1.1 from browser (e.g. Internet Explorer)

I've tried several times and the IP address always comes up as not found. Anyone else have this issue?

Or could someone suggest another way to secure the network?

Thanks in advance.

Not sure, but all my D-Link routers use 192.168 .0.1 as thier IP address. Try it, you should get to the log-in screen.