The "Informatics-InfNets-Forum" and "Informatics-EdLAN-Forum" configuration files and the corresponding -AT versions tunnel only Informatics traffic and EdLAN traffic respectively, leaving all your other traffic to go out through your ISP's default route.
We normally recommend those, as they're generally more efficient and robust, but they do have the potential issue that traffic to other sites will have your ISP-provided address, and so anyone basing authorization decisions on that address won't see you as being a University person. "Informatics-AllNets-Forum" (and ...-AT) is provided as a workaround for that situation. It tunnels all traffic over the OpenVPN tunnel, and so to the outside it appears that you have an EdLAN address. Unfortunately that does have some side-effects.