After long time ignoring my Debian, I installed 8.6 Jessie version of Debian last week on my Lenovo Y450.

Here is some troubleshooting and tweaking I’ve done for Jessie:

A. Driver for Intel Wireless Card

# vim /etc/apt/sources.list
  [add these list - for Indonesian user]
  deb http://kambing.ui.ac.id/debian/ jessie main contrib non-free
  deb http://kambing.ui.ac.id/debian/ jessie-updates main contrib non-free
  deb http://kambing.ui.ac.id/debian-security/ jessie/updates main contrib non-free 
# apt-get update && apt-get install firmware-iwlwifi
# modprobe -r iwlwifi ; modprobe iwlwifi

Source: https://wiki.debian.org/iwlwifi

[B]. Flash Player for Mozilla Firefox

https://wiki.debian.org/FlashPlayer