Again, as far as I am able to tell, it shouldn't be the antivirus, since I have added both installers, as well as the bat files etc to the trusted applications.
Something I am thinking about is the following - I tried to install Viscosity first; during the first install, I was asked whether I wanted to "install this device software" (as in the screenshot here:
https://www.sparklabs.com/support/kb/article/troubleshooting-viscosity-problems-windows/, under "Adapter Creation Failed or Adapters appearing as Unknown Devices"), and said no. Then, with Viscosity not connecting, I reinstalled it, once with an already existing installation, and then, this not working, first uninstalling and then installing again - however, I wasn't prompted to install the software again. Then, since it still couldn't connect, I moved to OpenVPN directly, but it still fails to connect - could the problem be a registry key that was edited the very first time I was installing, and has stayed like this since?
The link in the post immediately above mentions a RunOnce key, but it says it is for Windows 2000/XP; I have checked the registry, and such a key exists - however, it is there, not missing. Not sure how to proceed... 🙂