It’s a long story but I will try to be brief…after updating to Ubuntu 16.04 from Ubuntu 14.04 I started to suffer random connectivity problems with unknown root causes.
I review a lot forums and I tried a lot of different workarounds but, at then end, the solution was to change to WICD from the default newtwork manager.No problem since then.
The deatiled instructions can be found here:
sudo apt-get install -d --reinstall network-manager network-manager-gnome
sudo apt-get install wicd-gtk
sudo apt-get remove network-manager-gnome network-manager
Hope to be useful.