I did some testing and using the
.deb provided for
QT 5.6.1 I am able to build a working
domain-server on Ubuntu 16.04 LTS. Here are the instructions. I assume you did a basic install of Ubuntu 16.04 LTS. I am now using Linode instead of DigitalOcean because you get 2GB of RAM for 10.00 a month (The servers require more ram than they used to). So if anyone wants to sign up through this link and give me some credit to help drive me to keep doing what I do, here is the link: http://Linode.com
Now for the instructions:
apt-get update && apt-get upgrade -y
apt-get install git build-essential cmake freeglut3-dev libicu-dev libssl-dev
dpkg -i hifi-qt5.6.1_5.6.1_amd64.deb
adduser --system --shell /bin/bash --disabled-password --group --home /home/hifi hifi
su - hifi
git clone -b stable https://github.com/highfidelity/hifi.git
mkdir build && cd build
cmake -DSERVER_ONLY=TRUE -DQT_CMAKE_PREFIX_PATH=/usr/local/Qt5.6.1/5.6/gcc_64/lib/cmake ..
Let us know how it works out for you!