I am now at work and running Knoppix 5.0.1. As I thought, 5.0.1 does work on this network. By the way, the browser that I am running is Firefox. It did get renamed to Iceweasel in 5.1.1. You are most likely right that I have an IPv6 problem. For what it's worth, lsmod shows a rather large module named IPv6 running in the 5.x.x versions.