iOS 12 OpenVPN connection dirt slow, what is a better configuration?

Question

I am able to successfully connect to my Asus Router's OpenVPN server however, I pretty much get 0 bandwidth and can never navigate the internet.

Sample config file:

remote foobar.net 1194
float
nobind
proto udp
dev tun
sndbuf 0
rcvbuf 0
keepalive 15 60
compress
auth-user-pass
client
auth SHA256
cipher AES-256-CBC
remote-cert-tls server
auth-nocache

I tried adjusting the auth and cipher but that had no effect.

Answer 1

I switched over to the iOS app Passepartout for my OpenVPN connection. I was experiencing the same slowness as before on the official OpenVPN app.

When asking the developer of Passepartout about this issue, they linked me to the app's FAQ, https://passepartoutvpn.app/faq/.

At the time, they mentioned that they disabled compression through the app due to OpenVPN's VORACLE vulnerability, https://community.openvpn.net/openvpn/wiki/VORACLE.

Because of that, my connection was not compatible. I proceeded to remove compress from my OpenVPN config and was able to receive a connection and my bandwidth did not seem restricted.

Just listing here what I did to correct my original issue.

Answer 2

Have you tried running OpenVPN without sndbuf 0 and rcvbuf 0? According to the manual, when you don't manually set them they're set to the OS' default.

If this doesn't change anything, I suggest running your config with verb 3 added. The client and server seem to have some configuration mismatch and this should hopefully reveal it. If your router has server logs, it might help to check those as well.