Belkin wireless router...

First off, Hello there, I'm new hope you could help me with the following problem:

My housemates and I have reccently had a 3mb blueyonder broadband connection installed in the house. This goes into the cable modem, then, into our Belkin F5D7230-4 .

When there is a singular PC plugged directly into the modem, without the router inbetween, the connection is great... However, when it is connection through the router, (via an 802.11g wireless connection with "excellent" signal strength) it is significantly reduced . (to well below what it should be, even if we were all using it).

I had a look in the settings for the router, and disabled the firewall, but even so, it is still (almost every second) blocking an ip, (it says for DoS protection). This ip also happens to always always be the number 2 ip on the list if i tracert or pathping any web address! so I assume it must be the local hub or something.

The connection through the router is only any good for a couple of minutes after resetting it, and I have no idea what's causing it....

also, if I ping my routers ip, the connection between my PC and the router seems perfect, so it must be the router stopping connectivity beyond that.

Any ideas as to how I could solve this problem? any suggestions would be greatly appreciated!