Hi
The problem with USB 3 is unique to the Raspberry Pi 4 where there is some strange issue with SSDs on USB3 in combination with USB serial devices. And what seems to help is to move the SSD to a USB2 port which makes it slower but cures the problem. On your NUC it has no significance that the ports are USB3
The USB hub is also a Raspberry Pi thing.
The extention USB cable can help on all computers. It is a matter of moving the Conbee away from noise (electrical radio noise) item like the computer itself. If you move the Conbee away from the NUC but place it next to another device that makes noise then it does not helpor can get worse. The idea is to move the Conbee stick a bit away from anything electrical so the radio reception is less disturbed.
And you can also maybe place it a bit high so it is higher than most furniture. That can also increase the range.