Please can you advise what coordinator you are using, and ideally what firmware version it uses. If it is too old, then it may not work with newer Zigbee 3,0 devices and you may need to update the firmware.
Coordinator is “Ember”. I use the Bitron Video Zigbee Usb Stick AV2010/10. Baud 57600k, high Ram. Both Software Xon / Xoff and Hardware Flow Control work - I can pair hue motion sensors for example. Also hue E27 bulbs work.
How to determine the firmware?
Btw sorry for the bad spelling, it is because I write via Smartphone
It should be shown in the thing properties for the coordinator. At a guess, if you have not updated the firmware, then I think this stick will not work with some newer devices. They will join the network, and then leave again due to the security level supported by older firmware.
You reference quite old information and I think you can update this stick. Have you tried? Have you taken a look at the latest binding documentation as it references some links to new firmware that I think will be ok for this device (please be sure to select LATEST when viewing the documentation though).