I saw another post on the same subject and it appeared that the internet radio uses WEP settings to connect.
There appear to be two options available - either upgrade firmware for radio or change Home Hub to WEP.
I am attaching an article from BT about this particular problem, although your radio may not be a BT model. I hope this will be useful.
In relation to the Kindle it may be that you need to change the wireless channel - there are posts that indicate that channel 13 has problems but channel 11 is fine. To do this you will need to access the router's configuration pages. BT article here.