I am using MR600 V2 with jio sim in India.
B3 + B5 is working.
B40 + B40 is also working, which is good.
B3/B5 + B40 is not working. For that case only giving priority to B40 and it is working as B40 + B40. If the B40 is down or poor signal then your internet will be die. Also when file is uploading carrier Aggregation is not working.