Everyone in my neighborhood everyone connects at 26.4K. I have talked to about a dozen neighbors who all have the same problem. A telephone company repairman even plugged in his laptop down to the main junction box for our neighborhood and he only connected at 26.4K. The main junction box is about a mile away.
I have two computers with 56K modems. Both computers connect at 26.4K. It happens no matter which operating system I am using. It happens with Windows 2000, Windows ME, Red Hat 9, Red Hat 8.0 and Red Hat 7.3. I have 2 telephone lines and connect at 26.4 K on either. I have also tried changing Internet providers and that did not solve the problem either.
I live in a small city in the mountains of Northern Arizona. When I call the telphone company, they have made comments like "24.6K is plenty good." I once asked about DSL and she said "Oh, that is not available where you live." They have also said that they do not guarantee modems will work, that they provide voice grade communications. I do not have cable where I live either.
To compensate for the poor performance I have recently made a couple of simple changes to block many of the advertisemnts that appear on webpages. Not looking at as many advertisements makes the webpages load much faster. In both Linux and Windows I changed how those advertising related domain names are handled. I probably should not mention what I did because someone recently said that I not doing that in the proper way in Linux. So anyway, many of the web pages that I look at now have empty rectangles where the the advertisements should have been.
My main point is that the local telephone system is frequently what limits the connection speed not how the modem or computer is configured. Is this a common problem in other parts of the country?