Honestly, it sounds like the problem might be this particular install of this particular flavor of PCLOS. I'd do a fresh install from a freshly downloaded and slow-burned iso. (Mmmmm, food imagery. Slow-roasted isos.)
It may be that with your current install, you've tweaked yourself right out of the ballgame. Maybe the day you downloaded, that particular build had slightly different default settings. Maybe the small Chinese child at the factory didn't get the settings quite right on your new laptop.
Good news is, with it working on other distros and the button somewhat working, we know the problem isn't your computer, router, or IP. Rather than excavating your current setup with archaeological slowness, your time might be better spent downloading and installing the fresh iso. Unless you simply HAVE to know what's causing this, in which case, get out your tweezers, your whisk broom, your tiny shovel, and keep digging.
Bear in mind, I suggest this only because I'm completely unfamiliar with coding. Last year, whenever I'd get to a glitch, and I hit a lot of them, I'd just pop in the disc and reinstall. (2010 Gnome takes about TWENTY MINUTES. Try that with Win-Don'ts.) You've already gone much farther into the glitch-ditch than I ever bothered to. My suggestion is along the lines of taking the stickers off of a Rubik's cube and arranging them the right way. It doesn't qualify as a solution, but it does bypass the problem.
Should it turn out NOT to bypass the problem, try another PCLOS flavor. I'm confident at least one of them will work out of the box on both wfi and sound. Though you prefer KDE, do you prefer it to getting online and on with your life? Again,it might be possible to get your preferred distro, flavor and DE to work. A fresh iso install would at least give you the possibility that the Texquad took care of this discrepancy in the process of updating the build. Some Chinese kid having a bad day, I can't help you with. (smile)