Before "breaking" something or mess up with random settings (there are a lot hints around in debians and other forums how to set which parameter in different .conf files etc.) I have chosen to take latest package from https://packages.debian.org/jessie-backports/firmware-iwlwifi cause it is the latest available one regarding to https://wireless.wiki.kernel.org/en/users/Drivers/iwlwifi to be used with 3.16 kernel. And it's "integrated" in the Debian stable dependencies and not a package custom installed from outside Debian. I just use the settings which have been done by Debian-Installer, no custom changes in any config file.
So for now I am on "Intel Wireless 7265 firmware, version 25.228.9.0" to have a clean base to investigate and report further. If Maintainer needs more information or other logs please contact me.
