My Setup is as follows:

Notebook - 951G(1) - Wireless Bridge - 951G(2) - NAS
If I connect the NB via cable to (1) I reach throughput of app. 14MB/s,

Notebook - AP - 951G(1) - Wireless Bridge - 951G(2) - NAS
but as soon as I connect another AP (RB751U or Airport Express) via cable my throughput drops to less than 1MB/s. This is not a limitation of the AP's I can assure, because I tested them connected via Powerline to my NAS and get an app. throughput of 5 MB/s - this is the limit of my powerline connection. Same applies to the involved 951G's: if connected via powerline throughput is app. 5 MB/s.
I tried different Wireless Modes (any, 802.11, NV2), (2) is configured as ap bridge at 40MHz, (1) is configured as station bridge, (1) + (2) are both bridged to my WLAN subnet.

What am I doing wrong or what could to be done to overcome this shortage of throughput when using discrete AP behind wireless bridge?

Nobody around able to give me a hint?

no answer yet...

holiday season?

wrong question?

other reason?

Maybe you have created a mutual interference. Play with the frequencies, regulate the power and see spectral scan.