Frequent Modem Disconnects

There are quite a few factors that can cause your modem to disconnect from the Internet.  Here are some things to check.

  • (Very Common)  Is Outlook Express running?  It can be configured to disconnect after sending and/or receiving mail and will do so even if you have other Internet applications running.  To check if this is the case, open Outlook Express, click on Tools, Options, Connection, and see if there’s a check mark next to “Hang up after sending and receiving”.  If there is, and you do not wish Outlook Express to hang up, remove the check mark, click on Apply, and then OK.
  • (Fairly Common)  Other equipment attached to the same phone line as your computer.  Especially cordless phones, answering machines, and any other phones that use an electronic ringer, but including satellite receivers and even phone line surge protectors.  Any other equipment can possibly cause interference with your modem connection.
  • (Not as Common)  Modem drivers.  The V.90 protocol is only about 2.5 years old.  During the first year and a half after it’s release, it has undergone several revisions.  If your modem driver is over a year old, it could be causing a problem.  To update your modem driver, consult the documentation that came with your modem/computer, or visit your computer manufacturer’s web site.
  • (Not as Common)  Modems and phone lines.  Not all modems are created equal, nor are all phone lines created equal (due to distance from the phone switch that serves you).  Some modems work better on longer phone lines than others.  As an example, my parent’s computer can connect to the Internet at ~45,000 kbps, but due to the distance of the phone line, they received many disconnects and slow throughput.  When they would connect at ~26 kbps, they would not disconnect and actually saw better performance while loading web pages.  This is because the higher connect rate had many more errors, resulting in more retransmission of the data, more modem renegotiations, and retrains.  I live about .25 mi. away from them, and my modem consistently connects well at ~45 kbps.
  • (Not as Common)  Software Modems (win modems).  Software based modems require your computers CPU and Windows to function.  If your Windows environment is such that it requires more CPU time, (as in many programs running, low memory, low hard drive space, etc…) then your modem may not function properly.  It has been my experience many times, that turning off data compression on a modem can alleviate the problem with disconnections.  The easiest way to do this is to click on Start – Settings – Control Panel.  Double Click on Internet Options – Connections – Settings – Properties – Configure.  Change Max Speed to 57600 (Less if you’re on a long phone line, have other equipment attached to the phone line, etc.).  Click on Connections.  V.90 can take up to 90 seconds to negotiate a connection, So change the “Disconnect if not Connected within __ seconds” to at least 90.  Click on Advanced.  Remove the checkmark from “Compress Data” then click OK.  Also, something that can help on longer phone lines/lines with other equipment:  Click on Port Settings.  Change both the Transmit and Receive buffer to one less setting than the default.  E.g. On Win9x, move the slider left one position.  On WinMe change “High” to “Medium” and “Maximum” to “High”.

Those pointers cover the most common of the thousands of factors involved in a modem connection in my experience…