Brailliant Bi 40X and bluetooth

Hello,


I am not sure if this is the most appropriate list, but since I think my 
issue combines newish peripheral, brltty and bluetooth issues, it seemed 
like a good place to start :-)


I have been using a Brailliant BI 40X for the past couple of years with 
Debian Stable, but only over usb. This *mostly* works - except with the 
installer, where I have had to install a number of systems with sighted 
assistance (I may simply be choosing the wrong options, but there we go).


Although usb is workable, I would like to get the bluetooth working, and 
I have periodically attempted this, depending on levels of frustration, 
procrastination and entanglement with cables. I managed to get a 2018ish 
BrailleNote Touch working eventually, and indeed still can get it to 
work now that I know what I am doing, but I know that the bluetooth 
connection in the Braillan --X series is different (no PIN).


The behaviour I experience is this:


1. I  can pair and trust the device

2. I can initiate a connection which is reported on the device

3. When switching to that connection on the device, I get the dreaded 
"Braille Display" coming up, which means no input

4. On the laptop, a connection is notified, rapidly followed by a 
disconnection notice, and this then repeats until I stop the laptop and 
device talking to each other.


Consultation of logs reveals two possibly pertinent remarks in the 
brltty systemd log:


1. RFCOMM error (111), connection refused

2. hidOpenBluetoothDevice error (38): function not implemented


I did look into rfcomm and played with that for a bit, but not so as to 
achieve anything useful.


So, I am not quite sure where to go next. I'd be happy to dive into the 
code, but bluetooth is not something I have dabbled in. Any pointers or 
guidance would be really appreciated. OK, it might be a case of talking 
to HumanWare (I see they have a guide to usb connections on android, 
using brltty, and that suggests to me that the bluetooth situation there 
is also problematic - certainly I have never got that to work either), 
but I wonder if there is scope for implementing something without 
waiting for them, who seem to be in no hurry.


Fundamentally: is this a known issue, and are there steps that I can 
take towards resolving it?


Thanks for reading!


Isabel