You likely have to assign it an IP...like say if your dads IP is 23.222212 then yours should automatically be 23.222212.1 and any others a slight variation of it. I think you can also assign it a distinct IP also.

If you can find the disc/program for the router, and for the extention which is your computer and rerun it, that may help.

Not sure on a good site tho...i'd just google and have a look.