I think it is a shame that KDE had two major stable releases (4.0 and 4.1) which were unusable with very customary router software. The problem was known since the early betas, but has not been prioritized. I may have nostalgic memories, but I cannot believe this would not have happened in earlier release cycles.
A router update is not an option for many of us, as there are no updates for older routers available. The "buggy" hardware works with every other software on this planet, only KDE is affected. Do you really think that thousands of people should change their hardware, just because KDE sends out simultaneous IPV6 and IPV4 dns requests, even though my system is IPv4 only and all configuration options tell the system that this is so?
I fear that glaring usability bugs (i.e. KDE is unusable because of it) like this lead to a bad reputation of KDE, even though it is better than Gnome regarding its technical foundations.