Setup OpenVPN on Nighthawk R9000 router

Can someone please post an A to Z on how to setup VPN on Nighthawk router with OpenVPN. I've read the three articles below as well as many more on the OpenVPN site and youtube but nothing seems to be working for me. I recently reformated my harddrive and reinstalled Windows 10 but that didn't work either. 

Still get the following: 

WARNING: No server certificate verification method has been enabled. See ... for more info.

TLS Error: TLS handshake failed

How do I use the VPN service on my Nighthawk router with my Windows client?

How do I use VPN on my Nighthawk router with my iOS device?

How do I use VPN service on my Nighthawk router with my Android device?

Any suggestions are greatly appriciated. 

Cheers,