Evilnick,
It sounds like you are getting some interference from somewhere. I'm not sure if you
were aware of this but wireless technologies 802.11B and 802.11G (which you have, G)
run on the same frequency as 2.4ghz cordless phones and microwave ovens. So, if you
have 2.4ghz cordless phones in your house that could really mess up your signal, even
if the phone is just one and sitting in the handset not being used. This is what has kept
me from going wireless, for now. All my phones are 2.4ghz. I know this sounds odd but
feel free to do a google search or your own research regarding this technology. I've
read a fair amount about it and have noted many people saying they have problems with
their home network because of their cordless phones.
If you have 802.11B or G technology the proposed solution is to get a 5ghz phone (which
affects 802.11A wireless devices) or you can drop back down to a 900mhz phone. This
may not be your problem but when you said you put the devices close together and they
seemed to work fine that made me think of this.
I've also read complaints from people who had problems with their home networks because
of other wireless networks nearby affecting their performance.
Hope this helps!