airport extreme base station network add a switch

[singlemanhk]

Hi,

Currently my work network looks like this:

internet - router - airport extreme base station (3rd gen) -

the three outputs from the base station connect to a mac pro, a printer and a linksys sd2008 switch

the switch connects to a qnap 859, a qnap 659, a mac g3, a pc and a colour printer

all worked fine until recently when the base station data throughput dropped to single figure k/s and the mac pro running osX lion kept freezing and then crashing. having tested and tweaked, it seems as though the base station is freezing – which causes the mac pro to freeze - under high loads of data throughput especially when working on big files stored on the qnap storage while uploading large image files to customers

is it possible to re-arrange the network so the macs can access the external network storage without having to go through the base station which seems to be a bottleneck when moving lots of large images and pdf's around?

if i add another sd2008 like this: router-switch-base station-etc then nothing connected to the new switch shows on the network - suggestions?

or should the base station be able to handle these loads easily and the fault is with that hardware?

Thanks in advance for any feedback/help