Have you tried with your PC connected to daughter's aerial socket? It may not be connected to the aerial (I've known that happen).
Have you checked the ADSL speed that you're getting at daughter's machine?
Give speedtest.net a try. It may be a duff cable.
You're using a Belkin modem. Things may have changed, but I don't allow that brand in the house. I wasted several days of my life trying to sort a network, when the problem all along was a duff Belkin box. Several folks I "sorted out" had the same problem.