ovpn-dco-win VS openvpn-gui

We also back several OpenVPN related drivers, such as tap-windows6 driver, ovpn-dco-win driver, ovpn-dco linux kernel module. The tap-windows6 driver is the old Windows driver, which gives a pretty basic tun/tap interface. The DCO drivers are the next generation drivers, where more of the cryptographic operations are moved into the OS kernel instead of happening inside the OpenVPN Core components; which has the potential to improve the tunnel performance.

My point is ... if the OpenVPN server is correctly configured, it can perform quite well compared against its competitors. If you're running Linux, the openvpn3-linux client also supports DCO (OpenVPN kernel data-channel off-loading) now. There is also work happening on a Windows driver as well. How much performance boost DCO gives against ProtonVPN is unclear, but against OpenVPN Cloud (which also has kernel acceleration on the server side) it can improve the performance if your network link to the OpenVPN Cloud servers is good enough. OpenVPN 2.6 will come with DCO support for both client and server side too.

All that said, with the work being done in OpenVPN with the Data Channel Offload (DCO), it would probably be easier to get hardware support. The DCO implementations (ovpn-dco, ovpn-dco-win) offloads the data channel crypto operations to the virtual network driver, so the encryption/decryption/packet authentication happens entirely in the kernel space - which results in a noticeable performance boost. The tasks these DCO drivers does should be possible to more easily implement inside some dedicated hardware. But it won't be cheap.

I use OpenVPN frequently for work and the OpenVPN GUI client since forever has an annoying bug (Which is that with Windows with multiple keyboards layouts, especially Arabic, upon connecting with OpenVPN the Windows language will switch to the second rtl language) that they don't plan to fix (check this and this).

It is likely an issue with the 'cipher' options, if any, that are in your ".opvn" file. This is telling you that the opvn setting is not finding a matching cipher it is allowed to use. The fix per the message would be to add the Servers cipher to your options. https://github.com/OpenVPN/openvpn-gui/issues/381 https://github.com/OpenVPN/openvpn/blob/master/doc/man-sections/cipher-negotiation.rst

The big downside of the mobile SSL VPN solution (which is basically OpenVPN) is, you can not establish a vpn connection before the windows login. So Windows Group Policies are not applied immediatly and the user needs to manually connect to the VPN after the login. If OpenVPN would provide such a solution I would switch back to SSL VPN. There is still a feature request on Github since 2016 for this feature. See here: https://github.com/OpenVPN/openvpn-gui/issues/77

In addition we back several other open source projects, such as the OpenVPN GUI, OpenVPN for Android and OpenVPN 3 Linux ... these all provide various user interfaces on top of the OpenVPN Core component.