Wired connection causing wirless to drop

[woemler]

I have a home networking issue I am trying to troubleshoot and having very little luck solving. Here is my setup:

ISP supplied cable modem
Linksys WRT54GL wireless router running Tomato (default settings)
Apple Aiport Express as extender (for AirTunes only)
Desktop running Windows 7 with wired network connection
Laptops with Windows 7 and OSX with wireless connections
HP Printer with wired connection to router

When only the laptops and printer are using the network, everything is peachy. However, every now and then when the desktop comes online it will cause all other connections (it seems including the printer) to drop. Attempts to reconnect will either fail entirely or allow connection to the router but not the internet. If I switch one of the laptops to a wired connection, it will be able to connect to the internet just fine. The only way to get the laptops back online wireless is to reset the router and reboot everything.

Since my wife works at home and depends on an internet connection, I have been avoiding using my desktop all together when she is around for fear of bringing down the network while she is in the middle of something. Anyone have any ideas what might be causing all of this or what might be doen to prevent this? Thanks in advance.

 

[Guest]

Sounds like an IP address problem. Has the desktop been used for Window Internet Connection Sharing -- if so remove that.

You might also do the following:

Check TCP/IP Properties.

Start, Connect To, Connection, Properties, Scroll Down TCP/IP and highlight, click Properties and check that Obtain DNS and IP address automatically are enabled.

 

[woemler]

I am not using any connection sharing, as far as I know. I basically just set up the router with default settings and plugged everything in. I haven't played with any network settings at all.

Obtain IP and DNS Addresses Automatically are both already enabled.

 

[woemler]

If IP addresses are in fact the problem, would it be a good idea to use Static DHCP to assign a permanent IP to one or all of the computers on the network? The desktop seems to always have the same IP anyways, but maybe that would help?

 

[eibgrad]

I don't know jack about Apple products to be perfectly honest. But after looking at that list of devices, I decided to find out more about the Airport Express. Your description makes it seem far more innocent than it really is. That’s a router! Or at least it can certainly be used as a router. It suggests hooking it directly to your cable or dsl modem. It support multiple wireless clients, NAT, and, (here’s the key component) a DHCP server.

Now I don’t know how you’ve connected this Airport Express into your network, but it does have an Ethernet port and supports wireless, so one way or another, it becomes part of your greater network when in use. That suggests to me the very distinct possibility you’ve now created a DHCP conflict on your network. Any single network should only have one DHCP server or else devices will inevitably be misconfigured should they receive a response from the wrong DHPC server.

Again, I don’t jack about that Apple device other than what I read in the following document.

http://www.apple.com/airportexpress/specs.html

But it sure perked my interest to learn it was a lot more than just some simple media extender.

I suspect that’s the problem. I bet if you pull that Airport Express for a while everything will return to normal (well, it may requiring reboot your devices just in case one or two are misconfigured). At the very least, you should disable its DHCP server. Or maybe it has some “non routing” or “bridged” mode that effectively does the same thing.

 

[woemler]

We used to use the Airport Express as the primary wireless router in the house, but it was horribly unreliable, disconnecting computers at random and requiring daily reboots. I invested in the WRT54GL and flashed it with Tomato because I heard great things about its stability, and it has lived up to the hype. The Airport Express was added as an extender using the administration software that comes with it (Apple smartly planned for people using this in existing networks for adding AirTunes). Everything was rock-solid on our network after switching to Tomato until I added the desktop.

I read elsewhere that the IPv6-using Windows 7 Homegroup can cause wireless issues on network with mixed operating systems. I am testing this by disabling both IPv6 and all Homegroup services on the Windows 7 machines and seeing if I get any disconnects. I find it odd that if this is the cause, only the wired Windows 7 desktop instigates the connection problems and not the wireless Windows 7 laptop.

 

[eibgrad]

Again, if that Airport Express is on your network and still has its DHCP server active (and I've seen nothing to suggest it isn't), it's going to cause problems.

You have to understand that any given network should only have *one* DHCP server, and usually the one on your Internet router. If you have more than one, then there's always the chance the DHCP server from the Airport Express might respond first and result in misconfiguration of your devices. That could cause a loss of internet connectivity (because the default gateway is wrong), loss of internal connectivity (because more than one device has the same IP or has been placed on a different subnet), etc. And worse, it's very unpredictable. Everything will seem fine for a while as long as your luck holds out and the Internet router’s DHCP server responds before the Airport Express's DHCP server responds. Other times you're not so lucky, the Airport Express responds first, and bamm, you get misconfigured.

That's not to say you might not have other issues too. But again, I don't see anything so far that is preventing this DHCP problem from being at least a contributing factor.

 

[woemler]

I checked my Airport Express and it does not have its own DHCP enabled. It's set up to use our other router to connect and receive its IP address.

 

[eibgrad]

I checked my Airport Express and it does not have its own DHCP enabled. It's set up to use our other router to connect and receive its IP address.

Good. Although the fact it's using DHCP to get its own IP address from the primary router’s DHCP server is irrelevant. I'm only concerned if the DHCP server on the Airport Express is enabled, that could affect OTHER devices. But if it’s disabled, that ends that issue.

 

[woemler]

So after experimenting a bit with my home network to try to create the situations that cause the connections to drop, I have found that not only will my desktop coming online cause the wireless to go out, but my Windows 7 laptop as well.

Basically what this means is that anytime one of the Windows 7 machines comes online when the OSX laptop is already online, the wireless goes out. I have not seen the wireless drop when only a single machine is online and never when the OSX machine is coming online. This is looking more and more like Windows is causing the problems. How, I have no idea.

 

[max0r4axor]

Try disabling IPv6 on your network adapter on the pc

 

[Dark Lord of Tech]

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