Connections to Bielefeld University via VPN can only be established using the VPN software AnyConnect from Cisco. Its configuration is described below for the Windows operating system.
Open the link -> https://vpn-gate-1.uni-bielefeld.de with any browser and log in there with BITS username and password.
More info about the access data here.
AnyConnect can also be available on mobile devices with the iOS and Android operating systems.
-> Detailed instruction for iOS