Using Airpot Express to bridge existing ...

Hi list. Having some problems with my network since adding an Airport Express to it. Hoping someone can help me out.

My setup:
WiFi router (a Thomson 585n 802.11n model)
...connects wirelessly to...
Airport Express (newest model, the .11n one)
...connects over Ethernet to...
generic 10/100 switch
...connects over Ethernet to...
PS3, Xbox 360, DNS-323 NAS, and my TV

All four of the devices downstream of the switch experience intermittent difficulties connecting. They fail to get IPs, or they connect then drop the connection, or they simply fail to connect at all. This problem continues to exist on any given device if I eliminate the switch at connect directly to the Airport Express.

However, iTunes will happily stream music to the Airport Express without any problems I've seen. The LED on the front of the Express stays green. Pings from my Macbook to my Airport Express always work, even while the PS3 is failing to connect. So I think the wireless link is working fine. I conclude it's a problem within the Airport Express's bridging functionality.

Now, there isn't an awful lot I can change. The Express is set to "join wireless network" and "allow Ethernet clients". It's connection sharing is set to "Off (bridge mode)", which is right, I think (although that dialog is also ghosted and I'm not allowed to adjust it). That's the only setting I can do, actually -- "extend a wireless network" and "join a WDS network" both fail, probably because of my router.

Is there anything I can do to fix this or diagnose the problem further? I'm wondering if something is up with the MAC routing.

---

Orignal From: Using Airpot Express to bridge existing ...