This answer won't solve much but FWIW...

I scanned our database and most hits look like a patch from the HPRC is
needed. One thought was that the port was hung.

I 2nd John Burke's suggestion.

Since your profile is modem type 0 (none) the system should not care
whether anything is attached or not. You should be able to do...

FILE X,NEW;DEV=123;ACC=INOUT
FCOPY FROM;TO=*X

...and whatever you type would go out the port. Now, if you want to
aactually read the output, you need a terminal set to the correct baud
and parity. But, I would not expect an error message on the console
simply because there was no device connected.

If you are trying to log on, since the profile specifies speed sensing,
I would expect the port to adjust to whatever baud the terminal is set
to.

I assume you are attempting to log on from one of these terminals and
are seeing the message on the console. If so, please refer to my patch
comment above.