Troubleshooting Macintoshes for Disconnects
Testing the Line
You can determine whether your problem is related to a software conflict
or a line noise problem by using a dedicated data comminucations program
(i.e. Zterm,Microphone, etc.) and logging into our shell.
If you are able to maintain a connection, then disconnects possibly
reflect some conflict between MacPPP and your system.
If you are unable to maintain a connection you may be experiencing
line noise problems.
If you need a copy of Zterm for this test you can find it here.
Modem Init Strings
The correct modem init string is very important. Check your manual for a
Hardware Handshaking factory default, or click here for a list
of manufacturer-recommended strings by modem type.
Try adding S10=20 at the end of the recommended string to make it hang on
the line during loud line bursts. You can increase this number up to 255
although I wouldn't recommend much above 100.
Extensions and Control Panels that are not a part of the standard Apple
operating system can cause conflicts with data communications - especially
complex packages like MacPPP. System 7.5 has an extensions manager that
should allow you to restart with "System 7.5 Only." Try choosing this
option and install nothing extra except the Config PPP Control Panel
and the PPP extension. For System 7.0 or 7.1 you may have to accomplish
It is possible that a
connection problem could be resolved by upgrading to a newer dialler. You
may wish to start with the latest dialler from Steve Dagley, FreePPP
This program behaves similarly to MacPPP, although if you are using
$USERID$ and $PASSWORD$ on the connect script, you'll have to replace
those with your username and password.
Try reducing your Port Speed one choice at a time. If the Port Speed is
equal to or less than the speed of the modem, disable data compression in
your modem init string. Check your modem manual (for example, USR uses
&K0; to disable data compression). If any of these low speeds work, this
may reflect other conflicts between your modem and MacPPP. Try upgrading
to FreePPP, or try restarting your machine with system extensions and
control panels only, plus the PPP extension and Config PPP control panel.
Use of flow control can greatly affect connections in MacPPP. Start with
full flow control (CTS &RTS;). Some sources recommend CTS Only for any
port speed over 9600. Use None if the port speed is equal to or less than
the modem speed.
Variations of Port Speed and Flow Control can lead to a connection that
works best with your Macintosh and modem. Many modem manufacturers
recommend using CTS Only as a flow control option. Your modem's
technical support department may have specific recommendations for you
should you choose to contact them.