First time using Mr600v2 and i use it for my 4g lte broaband . 3days it was good speed up to 40mbs...but after 3 days...it comes slow and unstable connection. I do upgrade the firmware but still slow...speed up to 3 to 5mbs only and yet still unstable connection.  I tried to use my old ones router which is D'link..it is better speed and connection.

The speed up to 15mbs.

So what happen to Mr600v2 . How can i fix this issue?