Troubleshooting AirPort Extreme: Dropping packets with LinkSys routers

MacFixIt reader David Faust describes a problem corroborated by other users where system utilizing an AirPort Extreme card will repeatedly drop packets - resulting in extremely slow transfer speeds - when used with the popular LinkSys 802.11b BEFW11S4 router.

Oddly, this problem seems to have cropped up after applying the most recent AirPort Extreme firmware upgrade, which purportedly fixed a problem with encryption and LinkSys routers.

Faust writes:

"I ran across an interesting problem this weekend when my father in law came to visit with his PowerBook G4 17" with AirPort Extreme. He was able to connect to my wireless network that is running of a LinkSys 80211b router. The problem was that the wireless network was dropping packets. If I ran ping, I would lose anywhere from 10% to 90% of the packets.

"I haven't changed my router configuration in months and the Airport Extreme/LinkSys combo worked fine when he visited in March. The only thing that we can find that changed between visits was the Airport Extreme firmware upgrade that Apple released in mid-April. A powerbook with a regular Airport card and a PC with a 802.11b card work fine. The router is running the latest version of the firmware and was updated in February, so this appears to be entirely due to the Apple release."

Users experiencing this problem are presented with a full-strength wireless signal indication from Mac OS X, but nonetheless have severely crippled transfer rates.

A workaround that has proved successful for some is to throttle the LinkSys router's maximum throughput down to 1-2Mbps. To do this, connect to your router, go to Advanced, choose wireless and set "TX rates" to "1-2 MBps" down from the default "1-2-5.5-11 MBps".

Users are apparently not experiencing this problem with similar routers from D-Link and other manufacturers.

Feedback? Late-breakers@macfixit.com.

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