Yes also confuses me a bit, bit seems that way, as many other users did also run into this problem.
Yet, NordVPN actually has wireguard support, so i would try this, since its the VPN protocol of the future 
see: https://nordvpn.com/blog/nordlynx-protocol-wireguard/
Here is a "easy" setup guide for openwrt: Solved: nordvpn OpenWrt wireguard client
They also offer pptp, so if you are just after hiding your ip, this should also be faster.
PS: You might need to search or ask there support for a vanilla wireguard linux client settings/setup, since it seems they have written there own wireguard client... wtf.