You can still use Jessie and backports you just have to change a couple of things. I take no credit for this I found the fix online and am using it on my Jessie box. Change your sources to: deb http://deb.debian.org/debian jessie main deb http://deb.debian.org/debian stable-updates main deb http://archive.debian.org/debian/ jessie-backports main You can add contrib and non-free if you want Then run: echo "Acquire::Check-Valid-Until false;" | sudo tee -a /etc/apt/apt.conf.d/10-nocheckvalid Jessie sources will still work.
Now you are running Devuan which should not have been affected by the change to the best of my knowlege. According to: https://devuan.org/os/etc/apt/sources.list You need to add the following deb http://deb.devuan.org/merged jessie-backports main deb-src http://deb.devuan.org/merged jessie-backports main
In both cases you can install from backports with: apt-get install -t jessie-backports [name-of-package]