It was driving me nuts. The routers -- plural -- were dropping my connections unpredictably every couple of days. It's taken me months of trial & error configuration hacking and web searching.
I've solved it, but I had to dig deep into the Web and combine several different items of advice. There's a lot of well-meaning help out there, but not much high-quality free networking know-how; and this is a difficult topic to search, with too many similar variations that are close but simply not pertinent to my problem.
And WiFi trouble is increasingly common as more households get hip.
Multiple routers on the same network can step on each other's toes resulting in dropped Internet connections.
Configure one router as an Access Point.
There are other ways to extend a network's reach: radio signal boosters, hi-gain antennae, WiFi repeaters, sharing your neighbor's bandwidth.
I have used the access point solution before with dedicated hardware (though not two WRT54G's) and it now suits my situation here where we have a remote building that's already wired for Ethernet (not typical).
Configuring an access point is obvious to all my sysadmin friends and colleagues, but I was afraid to reveal my ignorance and suck their time on a long free support call with indefinite prospects of success. Also, I'm completely lost in most config interfaces -- being a regular joe CIO of the Living Room. My main fall-back has always been RESET. You can change one setting and have no idea what you've done and be forced to press RESET to go back to factory defaults. Until now, my ignorance has been a frustrated form of bliss. This is probably because a) I've never studied networking; and b) these devices work quite well out of the box with pretty much zero config requirements -- so why mess?
We've got two Linksys WRT54G's. They're old by now but that's what I'll use in the example; feel free to interpolate how the setup might work on your stuff.
This is a hybrid 4-port Ethernet switch combined with a wireless (B+G) router. Quite common, from almost all networking vendors.
Router 1 sits next to the cable modem and provides wired & WiFi signal to a Mac, a Linux machine, a Windows XP Thinkpad, an XO laptop, an iPhone and a wireless print server.
One of the four Ethernet ports goes into the wall where cat5 then runs 100 feet across the yard to another WiFi router, Router 2, serving The Cottage where I do ink-battles & Skype calls on a Mac Mini and listen to tunes beamed through a little wall-wart Apple Airport Express that outputs into a gnarly vintage hifi (which, like some kind of Brechtian time-machine, sounds best when Tom Waits or Uta Lemper are singing in German).
My problem was having to reboot (modems, routers and machines) several times a week, without knowing where or precisely why the router(s) were dropping IP Addresses. And in some cases, getting a connection on certain computers has not worked for long periods of time.
Here's What I Did
Configured Router 1 as normal, whatever that is. Or made as if it's the only router on the network. This means Router 1 is my DHCP server ("Dynamic Host Control Protocol" server).
When a device such as a PC on the network is turned on, it yawns, stretches and says, "Good morning," to Router 1 and the DHCP server inside Router 1 gives that PC a number, its IP Address.
These kinds of routers default from the factory to their own IP Address -- 192.168.1.1. [What's an IP Address?] Also, their default DHCP server settings allow for doling out 50 unique IP Addresses, starting with 192.168.1.100 and going up to 192.168.1.150 to any devices coming onto the network. You can increase or decrease the range if you want; I leave it alone. I think for these kinds of routers Linksys has a limit of 253 or some number like that.
Configuring Router 2 (as Access Point)
Change Router 2's IP Address to 192.168.1.2 (or to other than the IP Address of Router 1). You can't have two of the same IP Addresses on the same network.
Make the SSID name the same for Router 2 as for Router 1. SSID -- sometimes called ESSID -- is the name of your Local Area Network ("LAN"). For example, our LAN is called "Cocoa" -- named after a Chihuahua we know.
(These devices come with SSID set to "linksys" and you don't necessarily have to change it to get devices working. I learned to change it for security reasons and to avoid conflict with my neighbors' WiFi networks, many of which were left on default settings, in the close apartments when we lived in New York City. In a pinch I could get free Internet standing on the sink in the 2nd floor south bathroom at 58 West 88th St -- until she discovered her WEP settings.)
On Router 2, turn off or "Disable" its DHCP server.
On Router 2, unplug the Ethernet cable from the "Internet" port in the back and plug it into one of the four Ethernet ports.
Reboot the computer that's near Router 2 (your new Access Point) and it will pick up a new IP Address from the Router 1 and you are done.
As I said, using an access point is only one of several ways to extend the range of your home or home-office or small- or medium- or even big-business WiFi network. I'll be putting up explicit screen shots of the config interfaces when I have some more time. There's room to cover some basic WiFi security issues here, too.
If you're getting two new routers for this kind of layout, you would do well with a couple of these newer Linksys WRT54GX4 units. Or one of these and a cheap old dedicated access point -- ultra cheap at a garage sale, or on eBay, and you can upgrade the (Linux-based) firmware.
Apple networking products are also a dream to work with because they are attractive to look at and have the easiest config handling of any products anywhere.