Macbook is messing up entire house connection

Question

Hey guys,
I got a macbook a couple of days ago and it is causing a major drop of internet connection around the whole house. If I turn on my macbook and connect to the internet, most of my other family members around the house lose connection after a few minutes. Then, my macbook loses connection. Once I turn it off, the internet connection comes back after a little while. We also have a sony laptop that works flawlessly on the network until I turn on the macbook. I have a Linksys WRT54G Router and a cablevision surfboard sb4200 modem. Sometimes if reset both of these things the connection works, but then it goes out after a little bit of time. Please help me with this networking problem.
Macbook   Mac OS X (10.4.10)  

Answer 1

It sounds like you may be seeing a composite of two different problems.
1. The Macbook not staying connected. This is becoming a pretty well documented issue with the Mac OSX 10.4.10 update. At this point in time, Applecare's recommendation has been to go back to 10.4.9. You do that by doing an "archive reinstall" with save old files option turned off - which means that you lose what you have in your Mac drive partition - so back-up your personal work before resorting to that option! There seem to be major bugs with the Atheros WiFi driver that were introduced with 10.4.10. As of today, there still isn't a resoultion other than the archive reinstall. There is not an option as there is in Windows (ahem!) to roll-back the driver.
2. Other machines dropping off the network when you power up the Macbook could be that you are having the IP address assigned by the WRT-54G router being claimed by the Macbook as well as the Windows machine(s). This can happen if the WRT-54GS is powered off (even briefly) between the time it gives out an IP address to the Windows machine (the Windows machine stays powered up) and then you turn on your Macbook.
The WRT-54G does not keep track of IP addresses that it has assigned across a loss of power. The WRT-54G gives addresses out, if I recall corretly, with the valid time set to 24 hours, so the Windows machine will hang onto its assigned address for a day before it checks with the router again. I believe the DHCP server built into the WRT-54G is not smart enough to ARP for the existance of an IP address already in use on your network before handing out the address; the router relies on its table - which may not be all that trustworty. This bug can also happen if you have manually configured the IP settings on the machine(s) on your network and you have accidentally used the same address more than once.
Even if the DHCP client running on the Mac or Windows machine is smart enough to send out an ARP (address resolution protocol) request, it may not get an answer if there is a conflict. One of the operating modes of the WRT-54G is a private VLAN per machine so the machines can't see each other and hence the ARP check can't find duplicate IP addresses - but you will have a routing conflict if the same address gets handed out to multiple machines.
Best bet is to power everything off. Power on the surfboard cable modem, power on the WRT-54G, wait 30 seconds, then power on the computers. Make sure the wall power to the WRT-54G can't be interrupted. There is a slight chance you could have an intermittent wall adadpter for the WRT-54G causing it to reset and lose track of the IP addresses it has given out.
Other things to consider is that you may have your router on the same channel as a neighbor. The best way to figure that out is to download iStumbler from the Apple downloads web page and scan to see what access points are nearby. The only non-overlapping channels are 1, 6 and 11. If you have something on your channel (probably channel 6 if you never changed the default on your WRT-54G) showing more than 50% strength, you should change to channel 1, 6 or 11, whichever has the least signal from somebody else's access point.
I have a WRT-54G talking to several Windows notebooks, a 10.3.9 WiFi Mac mini and a Macbook. The Mini and Windows laptops are happy. It is the Macbook that keeps losing its WiFi connection.
Bill