Do NOT upgrade unless you are told to by Avantree support to do so.
This firmware upgrade version can solve below problem：-
Oasis Plus works as Bluetooth transmitter, digital optical connects to your TV/PC, dual link two Bluetooth headphones of CSR8635 Faststream code(Like Avantree 063), then you may hear noise from the headphones,we improve this from Lot 18H1.
Here is a step by step guide:
Step 1. Please download and install below app to your computer :-
Step 2. Please download below file to your computer and remember your saved path：-
Step 3. Open the doc file and follow the instruction step by step：-