Wifi signal keeps disappearing
October 20, 2010 3:56 AM   Subscribe

Wifi keeps disappearing from routers in coffee shop

I did an installation for a local coffee shop. They have had 2 previous people install wifi routers and every time they say it hasnt worked. When I first visited, I couldnt see their access point (from 2m away) but after I reset it, it came back. The next day, it had gone again.

(during all of this, hardwired connections are always fine, and the DSL line itself appears to be absolutely fine. There is a PC permanently plugged in and that never has an issue getting online)

I brought in a netgear DG834GT as I've never had problems with them before. I tested it at home for a couple of days - no issues. I installed it into the coffee shop and guess what... works for a while and then disappears. A hard reset brings it back for a while.

Currently they are resetting it every few hours but obviously there is an issue with wifi/radio.

From my laptop I can see a lot of access points nearby, its a busy street, there are maybe a dozen or so in range. Other factors, that maybe of relevance; it has a tanning salon at the back with several UV booths but they are 10m+ away and not between the coffee shop and the router. The router itself is kept under the counter, which is made of mdf. I've tried a couple of different channels also.

Any ideas?
posted by daveyt to Technology (10 answers total) 3 users marked this as a favorite
Change the ethernet cable leading to the wifi router and plug it into another power source.
posted by beerbajay at 4:16 AM on October 20, 2010

Have you tried one of those wifi scanners that shows you the signal strength and channels of all nearby wifi networks? Can't recommend a specific one for a laptop, I've only used one from the Android app market (called Wifi Analyzer).
posted by EndsOfInvention at 4:17 AM on October 20, 2010

Did you perform a WLAN site survey before installation? It's important to get a full picture of the wifi environment around your location, otherwise you are making uninformed decisions about frequency, antenna placement and power output of your AP.

Basically, load up NetStumbler or any other survey application and look at what's going on. Look at the signal strength and channel number. Pick the channel with the least congestion. If you're talking about 802.11b, in the US, channels 1, 6, and 11 are the only non-overlapping channels.

Most likely you've got the AP selecting a channel automatically. This is OK for more "quiet" environments, but in "noisier" environments, you can experience dropouts like this as the AP jumps from frequency to frequency.

There may be other sources of 2.4ghz interference like microwaves, but I think if you pick the clearest channel and set the AP to stay on one channel, you'll have a fighting chance. My final recommendation is to look into how you have the antenna oriented. Try different orientations and see if that changes the signal to noise ratio in your signal (also found in your wlan survey app.) If all that fails, maybe the router is toast.
posted by Geckwoistmeinauto at 4:38 AM on October 20, 2010 [2 favorites]

We've had this problem in our office building, where there are a bunch of wifi networks. We went out and spent a couple of hundred bucks on a higher quality / higher power router, plus added a repeater in the office. Seems to be helping for now, at least until somebody else in the building buys a more powerful router.
posted by COD at 5:57 AM on October 20, 2010

You may have checked this already, but there are two environmental things I'd be looking for:

1) Do they use the microwave a lot? Is this correlated with a loss in signal?
2) Do they use any sort of wireless speakers? These can wreak havoc on an 802.11b/g signal.

Other than that, is the SSID broadcasting, even if you can't get an IP address (or a connection to the internet)? That would indicate that the issue isn't your wireless access point, but its connection to the network.
posted by kdar at 7:50 AM on October 20, 2010 [1 favorite]

The coffee shop may or may not use a couple microwave ovens to heat stuff up. microwaves also operate on the 2.4 ghz range, and that will fuck with your wireless.
posted by Jon_Evil at 8:01 AM on October 20, 2010

All the above are good but if you're still stumped: get a small UPS and install that for the wifi router. They may have crappy power.
posted by chairface at 8:04 AM on October 20, 2010

If they have lots of customers with Bluetooth phones, that won't be helping either.
posted by flabdablet at 8:11 AM on October 20, 2010

I also sugegst a business oriented ap . D-link selles them in metal like cases. They are more money but last a lot longer.

The ones we use here at work are the dap-2590's They are dual band 802.11n ap's
posted by majortom1981 at 8:51 AM on October 20, 2010

you might also try, if possible, disconnecting the PC in case misconfiguration, employee bittorent and/or viruses are doing bad things. also public wifi in a coffeeshop is a helluva heterogeneous network environment, you might try running the wireless router without any connections and see if it craps out. finally, this is the sort of price/performance situation that ddwrt/tomato was made for, the software on the cheaper wireless routers is notoriously crap.
posted by ennui.bz at 10:25 AM on October 20, 2010

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