Domain – Can not access network drives after installing new wireless router

You mention both routers and access points in your question. An access point bridges wireless media to wired media (with many optional bells an whistles, too, on a real access point). A "wireless router" provides access point functionality along with additional functions to route TCP/IP between subnets (and provide network address translation, etc). I don't think you're looking for a second TCP/IP subnet and routing between it and your existing LAN subnet. I think you just want an access point, and you can use another router as a cheap access point.

Go get a second wireless router, and configure it as follows:

• Plug one of your computers into the new router's wired Ethernet ports w/ nothing else connected on the new router.
• Configure the new router to disable its DHCP server, and with an IP address that's in the existing TCP/IP subnet that your current network uses.
• Configure the wireless Ethernet functionality on the new router to match your existing router's SSID and encryption settings.
• Set the WAN interface on the new router to "DHCP client" and forget about it -- put a piece of tape over the port or something similar so you never plug anything into it.
• Disconnect your computer from the new router and plug one of the LAN ports on the new router into your LAN.
• The new router will bridge the wireless segment to the wired LAN, and clients of the new router will get DHCP and Internet access from wherever current wireless clients get DHCP.

We've done this fairly frequently with one Customer who wanted access points "on the cheap" by using Linksys WRT54G wireless routers and, through the procedure above, effectively disabling their "routing" functionality and just using them as wireless access points.

Alternatively, if you want to spend a little more money go get a wireless access point that doesn't have router functionality. It will need less configuration but will be a little more expensive. (Market dynamics are at play there... There's less demand for low-end access points than routers so the price of an access points ends up being higher than a router even though an access point "does less".)

If you've got nothing plugged into the "WAN" port (which is CORRECT), then the DHCP settings for the WAN are totally irrelevant.

You should also never see the 2nd router appear in your DHCP lease, because you've assigned it a static IP address, outside of the DHCP range of the first router (also correct).

What might be happening is that the router in question (WRT310N) might not permit this sort of configuration. I'm not familiar with that model, but I had a Belkin device once that would ONLY route traffic over the WAN connection, because it expected to be the only device on the network.

The surest way to find out what's going on (or rather, not going on) would be to use Wireshark on another PC to watch what is being sent/received over the WiFi connection. If it's not even TRYING to connect, then it might be that the device just won't do it. Otherwise, it might be able to narrow down where the issues are arising.