Note1: 
The new image file (*.con) is encrypted which starting from v6.30.016. 
It needs upgrading to f/w v6.30.16 (.hex) first if attempting to upgrade from (v6.20 or older) to v6.30 (.con).
Use v6.30.016 backup encrypted firmware file (.con) to upgrade firmware

Note2:
The configuration saved from v6.30 is not compatible with f/w v6.20 or older. It might cause unexpected settings or behavior. 
Please don’t try to load new configuration running on old f/w v6.20 or older. 

Note3:
The configuration saved from v6.20 or older is compatible with f/w v6.30. It's working to load old configuration running on f/w v6.30.