Cable Modem Slower Than DSL with one Application

[Dennis D]

have recently installed a cable modem (Motorola from Cox.net). It supplemented my wireless DSL modem. I can now alternate between them. I ran speedtest.net and the new cable modem was from 15-17 times faster than the wireless DSL. My browsers work faster, and files download much faster. I also have a couple of web sites. I use a shopping cart that gave me a desktop application for interfacing with the shopping cart's back office. It uploads and downloads all of my products on the web site. Timing how long things take, it turns out if I use the cable modem instead of being 15 times faster, it is 1/3 the speed of the DSL line. I have received various suggestions on how to fix this like, increase the size of virtual pages, uninstall my software firewall and antivirus program, which I have done, and no changes.

Cox Cable is unable to figure out what the problem is. The people who wrote the software for my shopping cart said that no one else is experiencing this problem, and they have users logging in using dial up, cable, dsl and T-1. They claim their back office uses the same protocols as browsers. I went to a Cable Forum, but no one had any suggestions.

I notice, using Task Manger Network Screen, that the percent utilization of the dsl line is 12% or so while the cable is less than 1%, when I'm using the back office and communicating with the shopping cart's servers.

I have a feeling that the problem is my software, but I'm not sure where to begin looking. I'm running 32 bit Vista Ultimate with SP1, on a 1 year old lap top with 4GB of memory. The laptop is capable of running 64 bit Windows 7, but I need to solve my problem before this software is available to me.

Does anyone have any suggestions or questions that might help?

Thank you,

[Suspishio]

I haven't got the clearest picture of what's talking to what. But - I think you're using commercial software to talk to third party servers.

Is it possible that the servers are throttled and won't deliver at 20Mbits/sec? Each port could be throttled to, say, 2 Mb/s. Sure the software people say that other users are on cable, but you haven't said what speed they experience.

I do hope it's not one of those awkward MTU issues; you could check the MTU size on the DSL vs Cable and if they differ, then, depending on the way the software you are using is written, your data could be split into several packets in one system and not the other. This will add delay and then there's the question of what the server does with the fragmented messages. Nice can of mush that would be and I hope it isn't the case.

[Dennis D]

I'm not sure what you mean by commercial software. I'm running a shopping cart desktop application that connects to the shopping cart software servers. I'm positive that other cable users are not having this problem as I have discussed it with several of them. It just seems to be unique to my computer.

[Suspishio]

The shopping cart desktop application is the commercial software to which I'm referring. So that's clear - i.e. what you are doing.

If you are talking to other cable users, then with my final paragraph of post #2 in mind, perhaps you can examine differences in cable modem or router settings between yourselves. Is there a cable modem that connects to your router?

[Dennis D]

I'm not using a router. My cable modem has an RJ45 out jack which I have connected to my in RJ45 gigabit port, with a cat 6 cable. If I every get this direct connection working correctly, then I will get a wireless router for my wife's computer to also connect with the cable modem. My computer is a Qosmio, G45 AV 690 with 4GB RAM, but I'm not sure what settings I should also be checking