3Com part number is 3c421600A. Service says that the 'A' is significant. This is a discontinued product, 3Com may yank web pages which have the firmware and flashing instructions.
Console settings are 38400-8-N-1 instead of 9600-8-N-1
The unit comes with an old 1.x version of the firmware which does not do web access. You must flash a 2.x firmware before restoring the saved setup.
Firmware flashing is done from the terminal console. You need a terminal program which does Z-modem to upload the file (which is the default in Hyperterm). Make sure you know where the rasboot.dmf and ras1500.dmf files are on your system ahead of time.
Follow the instructions "Upgrading the Firmware on the RAS 1500 Unit Base Unit" in the pdf you will find in ras1500software25.zip (stored, as of this writing, in ~uxilium/dave/projects/RAS1500) Some of the commands are time-critical and can only be issued within a narrow window during the boot-up/shut-down sequence -- reading through ahead of time is a good idea. Also note that in instructions, commands such as AT{Z} are literal (ie, type the '{' characters). Flashing is slow, as it takes about 15 minutes to dribble a 2.5Mb file through a 38.4kbps straw.
This is a collection of techical information, much of it learned the hard way. Consider it a lab book or a /info directory. I doubt much of it will be of use to anyone else.