Digital Sender 9100C - forgot password. Want to restore to factory setting to enter new IP address

[Rizlaw]

Before posting here, I tried HP CHAT support. They said my 9100C was OBSOLETE, no longer supported and they weren't trained to answer any questions about it. Thank you "ANNAPURNA" for being so helpful.

I've had this unit since I purchased it it new in 1999. I originally used it under Windows NT in my office. I discontinued using it when I retired, but I kept it. I no longer use Windows and switched to Linux. HP never made Linux software for this device. (I'm not certain trying to run the HP software in a Windows VM would work).

For some reason, when I used the  9100C, I entered a password to protect against unauthorized use. I originally set it up for a Windows LAN using 192.168.0.X. I now have a different set of LAN addresses for my current router, Linux PCs and HP LaserJet 4000TN printer. I can not get into the setup menu because of the password protection. The owner's manual offers no help on this situation - apart from stating that pressing  "CTL+ALT+r" is supposed to erase the password (not clear which password the manual refers to). Unfortunately, the key sequence doesn't seem to work for djeleting the master password.

Anyway, before I consider a perfectly good piece of equipment a total loss, I thought someone on this forum might know whether there is a secret combination of keys on the 9100C that can be entered to reset this device to factory defaults so that I can enter new information. I can't imagine that such a key combination doesn't exist because I couldn't be the only one to have such a situation happen.

Thanks for any helpful advice.