Well, no, if I disabled IPv4 I would cut myself from half the internet. The more plausible answer is that my system simply prefers IPv6. You know, getaddrinfo is asked, v6 returned, Bluetit asks for IP using that, voila, IPv6 result. Unless you explicitly programmed it to show both. But I never witnessed it print both.
Well, as written, I would've noticed right away if I ever lost the native v4 connection. In fact, I'm connected to Kitalpha right now over v4 only.
I've got this Kitalpha profile for that, and I use with with OpenVPN 2.5.0:
client
dev tun
resolv-retry infinite
nobind
persist-key
persist-tun
auth-nocache
verb 3
explicit-exit-notify 5
remote-cert-tls server
data-ciphers AES-256-GCM #:CHACHA20-POLY1305
data-ciphers-fallback AES-256-CBC
comp-lzo no
proto udp4
auth SHA512
fast-io
rcvbuf 524288
sndbuf 131072
remote 91.214.169.71 443
route 192.168.0.0 255.255.0.0 net_gateway
<ca, cert, key, tls-crypt>
…
</ca, cert, key, tls-crypt>
.