Long shot - Edgeport on a Raspberry Pi

Hello - I realize I am pushing my luck here but I am running a bunch of Raspberries and need multi serial port capabilities to support some old terminals (teletype 33 amongst many others)

Edgeports are plentiful on the ebays and they did seem to work at one point on Linux.

My Edgeport/4 works great for about 5-15 minutes then I get “cannot send clear loopback command” in dmesg.

I copied the firmware files intop /lib/firmware/edgeport and the ttyUSB0-3 appear as one would expect.

Googling “cannot send clear loopback command” appears in some code written by a bunch of folks many years ago who are unable to help when I reached out.

So - two questions!

  1. Anyone have any tips for me?
  2. Anyone got any other suggestions for multi-port serial converters that work on Raspberry Pi OS at SLOW data speeds such as 110?

The only multi serial port device (supporting 110 baud) I have success with on my Raspberry is the Keyspan 4-port USA-49W devices, but these are pretty ancient as well and I think I purchased the last couple!

thanks in advance!