OpenVPN only works as long as System is not rebooted

I hope this is the right place to ask this.

My University lets students download a preconfigured executable of OpenVPN, where the settings are already branded in. Once you installed it, you just enter your credentials and you are coected.

However, I noticed that it doesn't work anymore after the system is has been installed on is rebooted. If I install it, I get a successful coection with the VPN and can use it. If I restart my Laptop, it does not work anymore, but the Icons in the Tray still show a green screen. If I then uninstall it and reinstall it, without rebooting, it works again.

The only difference in the log window when it's coecting, I notice when it does not work, one of the lines would say "Failed ARP Flash on Interface" or something like this, when it works this exact same line says "Successful ARP Flush on Interface".

I'm ruing Windows 10, this has been a problem since Windows 8.1 though.

Any ideas on how to fix that? I've tried both the x64 and x86 installers my University offers.