Gender Serial Changer

why does my external 56k modem only connect at 28.8?

It is a USRobotics 56k modem with X2. It is connected to the computer with a 25 foot 25 pin double female serial cable then a 25 pin male to 9 pin female converter and then a 9 pin gender changer (this is the only working combonation I had readily available, could the cable length be the problem?)The compuer is running both windowsXP pro and Ubuntu Linux. I'm having the same speed issue on both operating systems. The compuer is also running two interal softmodems, with no connection speed problems on either internals.

I'll assume you've use the same phone line and same destination telephone numbers for all three modems involved (two internal and one external).

Are the internal softmodems also X2? As I remember, X2 was a 56 kilobit/second protocol that pre-dates V.90, and was would only achieve 56K with other X2 modems. With any other types it only would negotiate a maximum of V.34 protocol at 28.8. K56Flex was the other pre-V.90 protocol. Do you know if your remote location is operating modems that work with X2?

CompTIA A+ 220-601: 1.1 - Connectors and Adapters