Ask the Wi-Fi Guru, Episode XVIII

Ask the Wi-Fi Guru, Episode XVIII

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Written By Eric Sandler

By Aaron Weiss

August 11, 2009

Our monthly Q&A; series offers advice to those seeking help with home or small business WLANs. This month our Guru offers advice on the common issues of range extension and bridging, among other things.

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Our monthly Q&A series offers advice to those seeking help with home or small business WLANs. This month our Guru offers advice on the common problems of range extension and bridging in a couple of different scenarios.


Three cheers for free Wi-Fi! Earlier this month, Verizon joined a small but growing list of broadband providers who have extended free wireless hotspot access to FiOS and DSL subscribers. To be fair, perhaps Verizon deserves only two cheers, because the service is available only to Windows-based devices and requires their own proprietary software to log in. Starbucks is offering two hours of free wireless to customers with Starbucks loyalty cards. And Barnes & Noble has dropped its fee-based hotspots in favor of open, untimed wireless. 

Of course, free Wi-Fi is nothing new especially at smaller, independent stores competing with the big guys—but the ranks of paid hotspots seem to be a dwindling lot. While the right to check e-mail anywhere may not exactly rank up there with social causes like civil rights, we may yet see the day when ubiquitous free wireless access is as commonplace as water fountains and restrooms.

Q: Hi I am relatively new to wireless networking. What I want to do is basically this:

1. Extend the range of my wireless network on both basement (router 2) and second floor (router 1).

2. Be able to connect via Wi-Fi to the Internet using my laptop from either router.

3. Create a wireless link of some sort between the two routers, in other words, I don’t want to run wire between the two routers.

4. Avoid the problem of “half the bandwidth” on router 2.

5. Be able to connect wirelessly my PS3 from the basement to router 2.

Okay, these are my requirements, what, if any option can I use?–Jorge

A: To recap, it sounds like what you want is a wireless network which supports roaming between floors, but does not cost bandwidth for devices connected to the secondary router.

In a network that supports roaming, your wireless device (such as your laptop) will connect to the strongest signal, and hopefully switch as necessary seamlessly as you move around the space. For this to work, there needs to be at least two wireless access points, each configured with the same SSID, identical security parameters (protocol and password), but different broadcast channels.

Indeed, you could set up a roaming network either using WDS or a wireless repeater, but both come with a cost. The secondary router will be doing double duty as both a wireless client—to receive a signal from the primary router—and a wireless AP—broadcasting signal to associated devices. Because the secondary router has only one internal radio it must operate at half-duplex, meaning it switches between receiving and broadcasting. The effect of this is that the available LAN bandwidth is cut in half for devices connected to this secondary router. So neither (a) nor (c) of your options will solve this problem.

Option (b), the wireless bridge, gets us closer to the solution—but with a twist. What you need is a third router!

Or, another way to put it, is that your secondary router should really be a set of two routers—let’s call them router 2a and 2b. Router 2a will be a wireless bridge. It will receive the signal from your primary router, assuming it is configured to match your primary router’s settings (SSID, channel, and security). Be sure to assign router 2a a unique IP address compatible with your LAN (such as if your primary router is

Router 2b will be plugged into a LAN port on router 2a using an Ethernet cable. The two routers can literally sit right beside each other, so the cable can be very short. Router 2b will be configured as an AP (access point). In other words, you will disable the WAN, DHCP server, and firewall on router 2b. Manually assign router 2b another unique IP address compatible with your LAN (such as Configure router 2b’s wireless settings to the same SSID as your primary router, with the exact same security settings, but manually choose a different channel.

If your primary router is set to broadcast on channel 6, configure router 2b to broadcast on channel 1 or 11.

By using two physical routers at your secondary location, you are essentially building a full-duplex repeater using Ethernet to connect two separate radios. This way, you can maintain your ability to roam on a single SSID, while not losing bandwidth for devices connected to your secondary location. 

Q: Hi mate! I have two DIR-300 routers, one with its original 1.04 firmware version and a second with DD-WRT firmware V24. I wanted to expand my network by connecting them somehow. Repeater Mode seems not to work with DD-WRT on DIR-300 models.

I have a chance to connect them wired to get more devices connected from the second one. What mode would it be and how can I do it? I have a wireless network already working, one router, and one 8dbi antenna. Can I connect both routers wired? And have both routers working as an AP? Do I have a better choice, like just buying another antenna? – Ignacio

A: Sometimes repeater mode in DD-WRT is difficult to get working—it could be a combination of the specific router model, the specific version of DD-WRT, or something more mysterious. If you’ve given up on DD-WRT repeater mode, you still have options.

One option is exactly what you describe—connect the two routers by wire. You absolutely can do this, making your secondary router into an AP. As described above, to make your secondary router a “dumb” AP, disable its WAN connection, DHCP server, and firewall, and manually assign its LAN connection a static IP compatible with your network. Set up the wireless parameters to match the wireless settings on your primary router.

If you want to support roaming between APs, set them to broadcast on different channels. If the distance between routers is very far and you don’t care about roaming, then the broadcast channel may not matter.

I happen to like wired solutions wherever possible—sure, this is a Wi-Fi column, but using wired connections where you can is an effective way to eliminate problem variables. In this case, if wiring the two routers is not too complicated I would prefer this option over trying to improve your signal reach with a different antenna.

Q: I own an on-site computer service company. I heard about flashing a Linksys router to make it do tricks. I only need it to have a stronger signal. I was told by a tech friend that I could flash it and it would give me the ability to change the…?? (I can’t think of the term right now…frequency??) …to a higher one so that the signal would be stronger. I have a customer that has a connection issue for an unknown reason. Wireless access is needed in the pool house which is maybe 100ft through walls. There must be something interfering. Do I have to have two router/AP’s to do this or can I just flash the existing router to be a new, stronger animal? – Patrice

A: Depending on which model of Linksys router you have, you may be able to flash it to either the DD-WRT or Tomato firmware instead of the stock software. Your friend was probably suggesting that you could increase the router’s output  power. The output power of the router can roughly be thought of as how loudly it “yells” to the outside world.

It may seem logical that the louder a router “yells” the more devices can hear it. A good thing, right? But think about a yelling person—if you yell too loud, it can actually be more difficult to understand you. Your voice gets distorted. It is similar with routers—as you increase their output power, you also amplify noise in the spectrum. You could very well end up producing a louder but noisier signal, making it even less useful than a lower output power.

But, like with many things wireless, it depends. There are so many local environmental factors at play.

The stock firmware for Linksys routers usually pegs the output power at 28mW. The Linksys firmware does not let you change this. However, Tomato and DD-WRT firmware do. Theoretically, you can pump up the output power to 250mW, but this is not recommended. Not only will the signal be very noisy, but the router will run very hot. Increased power means increased heat, and these consumer-grade routers are not designed with active cooling. Basically, you could fry the thing—if not immediately, then eventually.

That said, changing the power output to slightly increase your range is worth a try. When you flash the router to Tomato or DD-WRT, its power output will probably be set around 42mW (the defaults for these). You might actually try backing off a bit and lowering the output first—maybe you are already picking up too much noise. This may not work, but there’s no harm in trying less power.

You may find that the higher default output of the replacement firmware does the trick all by itself. If that still doesn’t work, I would be hesitant to go above, say, 80-ish. If you still can’t get the range with that level of output, then this doesn’t seem like the solution to pursue.

If your Linksys router has a detachable antenna, you can also consider swapping it out for a larger, more powerful replacement. 100 feet is not all that far, and a larger antenna perhaps combined with a bump in power output would hopefully get you there.

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