Slow Internet on wired connection, fast wireless on same network

[armhol]

Hi,

My Internet has just been upgraded from 2MB/s to 10MB/s. To confirm the upgrade I have used www.speedtest.net to test my upload/download speeds with Firefox and Safari. I have 2 computers on my network which consists of a cable modem connected to a white airport base station with 128 bit WEP encryption in 802.11 b/g compatible mode. The 2 computers are a dual 2.8 ghz MacPro which is wired directly into the Airport base station by Ethernet and an iMac 1.83 Intel core 2 duo. The much faster MacPro only achieves a download speed of 5.5MB/s over its wired connection while the slower iMac achieves 9.8MB/s - very close to the advertised speed over its wireless connection. These are consistent speeds not one offs so I am wondering why the difference? The MacPro is my main machine so I'd like to have the best speed possible on that. Any ideas? What can I try?

Thanks for reading all that, I've put in as many details as possible, I'm really stumped!

Thanks in advance,

Alan.

 

[Lanbrown]

Same version and release of OS X on both machines?

 

[armhol]

Yes, same system on both machines OS X 10.5.7. The Airport base station is running software version 5.7. I just connected the MacPro directly to the cable modem bypassing the Airport base station completely and no change, I'm still only getting 5.5MB/s download.