Bluetooth no longer sees forgotten device

I just upgraded to IOS 11.4.1 and Bluetooth is giving me problems.

I have a app that communicates with my Respironics Dreamstation cpap unit via Bluetooth.

It has worked perfectly for over a year. Yesterday I upgraded to 11.4.1 and the app will not now connect.

I told IOS to forget the device planning to re-pair and now the IOS Settings app will not seethe cpap at all!

I have the same problem now on my iPad Pro 9.7 which I also upgraded

Interestingly, I have a Samsung Android tablet that sees the device, pairs correctly, and works just fine.

I have:

Turned Bluetooth on and off - no luck

Rebooted my phone - no luck

Reset my network preferences - no luck

Reset ALL preferences - no luck

I installed two Bluetooth finder apps from the App Store and they both find my cpap showing the same device name as before PR BT 3C06

iI am out of ideas and very surprised that this problem has cropped up