Like probably every other computer geek out there, I do a certain amount of helping friends set up their home systems. This particular friend knows nothing about networks and firewalls and the like, and just wanted something secure that would allow her to have a reasonably safe Windows box and the daughter to have a reasonably safe and virus-free Windows laptop. The easy bits were installing the spyware detectors (Ad-Aware and Spybot S&D) and the virus checker/utilities (Norton SystemWorks); the tough bit was getting the routers to work.
The system that made most sense was to feed the DSL into a wired ethernet router with a built-in firewall (the D‑Link DI-604 has a reasonable price point and an integrated firewall) and then set up a wireless point for the daughter’s laptop. So my friend got a Linksys wireless router (no firewall). We have this system at home, though with different hardware (Linux firewall + Airport wireless) and it works just fine. So I wasn’t expecting any oddities. I found the support page on the Linksys site that said to turn off the DHCP server on the wireless router, and to give it an IP address that fitted in with the IP setup of the wired router. That was easy enough to do. But somehow the laptop just never managed to sync up.
Ah, how good it was that I allowed more time than I expected to need to set it up! My basic idea was that ethernet comes out of the DSL mode, goes into the wired router in the uplink socket, then a cable comes out of the wired router and goes into the uplink socket of the wireless router. Still seems logical to me, but in this case my logic was completely wrong. Fortunately Linksys has live chat to tech support that works on a Saturday (good move, people!) and Melrose didn’t need very long to figure out the problem and tell me to put the cable coming out of the wired router into one of the 4 regular sockets. This worked just fine; the laptop synced up, my friend (and her daughter) are happy and think I know exactly what I’m doing, while I’m still slightly baffled and wondering what’s wrong with my simple hose-pipe analogy of internet connections. Still, I now know empirically what to do, so that’s the important thing.