Can't help with tap/tun. Other than that one project I mentioned for a client, I've never used OpenVPN on Windows. My implementations have been static tunnels between machines running Linux, and all of them use tun.
Glad you got it running.
How did nmap go? I scanned 103.125.207.43 from one of my public servers and got nothing. Is that still the remote server's public IP address? If so, it doesn't show any exposures to nmap.
Code:
# ping 103.125.207.43
PING 103.125.207.43 (103.125.207.43) 56(84) bytes of data.
4 packets transmitted, 0 received, 100% packet loss, time 3674ms
# nmap 103.125.207.43
Starting Nmap 5.51 ( http://nmap.org ) at 2020-06-10 08:30 EDT
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 3.16 seconds
# nmap -P0 103.125.207.43
Starting Nmap 5.51 ( http://nmap.org ) at 2020-06-10 08:30 EDT
Nmap scan report for 103.125.207.43
Host is up.
All 1000 scanned ports on 103.125.207.43 are filtered
Nmap done: 1 IP address (1 host up) scanned in 201.51 seconds