How can I downgrade my Blackberry Q10 10.3.1.1779?

I upgrade my blackberry Q10 to the above OS version and since then its just giving me problems,

i cant make calls sometimes, saying no network connectivity, sometimes people tell me they cant call me, sometimes the icon for network connectivity on the homescreen just dissapears, says no network.

please advise me on what i can do to sort this problem.also if its possible for me to downgrade the OS.

Which method did you use to upgrade the device software on your phone? For example, over-the-air (OTA), via BlackBerry Link, a third-party tool such as Sachesi, or an autoloader?