Unable to connect to OpenVPN from Asus Router

[khadanja]

Working fine when configuring on OVPN Desktop client and also on mobile app.
I can import .ovpn file Private Internet Access into Asus and it works, just FYI.
Trying to set it up on Asus router under VPN Client setting but it won't connect. On Asus side I see this in log when trying to connect -
Oct 29 17:55:48 68U ovpn-client5[1992]: /usr/sbin/ip addr add dev tun15 local 10.8.0.22 peer 10.8.0.21
Oct 29 17:55:48 68U ovpn-client5[1992]: Linux ip addr add failed: external program exited with error status: 2
Oct 29 17:55:48 68U ovpn-client5[1992]: Exiting due to fatal error
Can provide more info if required, I just exported the ovpn file and imported into Asus router.