For any user that already has most of their network set up, and just needs to add wireless access (without adding more NAT, filtering, another layer of DHCP, etc.), this is probably the right article for you. (this article was originally titled Wireless Bridge Mode, but that term seems vague at best, or even incorrect)
Switch mode for a wireless router means that it no longer performs NAT, it doesn't serve DHCP addresses, and basically, it just passes the network connection along to wireless clients that are connected to it. This is not the same as bridging, WDS or access point mode.
The default settings on the 7501 have "NAT" and "Private LAN" turned on, and do not allow you to see any network other than what is served by the router. In addition, the way that the "Routing" webif works, it is difficult for your router to see the internet once you set it to "Public LAN". This is a problem if you have a larger (wired or wireless) LAN and wish to see and browse all of it, and allow your 7501 to set its time & date properly. Here is one way of getting around this stock limitation of the router.
We will assume the following:
1. Go to Advanced and click Yes on the Warning!! page.
2. Disable Private LAN, and enable Public LAN (but with the DHCP function disabled). Use a static IP setting and enter subnet, gateway (of your cable/dsl modem) and other needed settings. Save your settings and make sure you can still connect to your router.
3. Go to My Network -> Network Connections -> VersaPort:
4. Unplug the WAN ethernet cable and move it to an unused LAN ethernet port. Go back to the web interface page, and make sure you can still access your router. You may want to reload it to confirm that you are still properly connected. Also make sure that you can still load a regular internet page, such as yahoo.com.
5. I had to do this step for my network - this step may be optional for some users, but I had to do it. Via telnet from the 7501, add a route default route to your routing table. For my network, I did something like this:
where 192.168.xxx.xxx is the IP address of my main router/gateway/DSL modem.
I eventually added the following commands to my firewall-startup script:
The problem that I was having is that my router could never connect to an internet NTP server, consequently it could never set its own time when booting. Adding the route solved the connection problem. Unfortunately, while the stock webif does all allow one to add a persistent route (saved to flash memory) it doesn't allow for adding this particular structure of route that I needed for my situation.
6. If all else fails, and you have no connectivity, your network may have some odd topology. In such a case, just reset to default settings as shown in your 7501 User Manual. Then start again at step 1. You may want to do some reference and get help from someone who is network-savvy.