Local Wireless Network - Strangled

I have a wireless router for internet plus a wireless AP connected to my Dreambox.

I used to be able to download files from the DB at 10Mb/s,

limited by the 10Mb/s port on the DB, the router and AP are 100Mb/s.

Now downloads are crawling, this evening only 1mb/s, or less.

I have checked with Net Stumbler and cannot see any other wireless networks

on the same channel, channel 4, not the default.

Any ideas.

Big files are taking ages to transfer and it is a pain.