You can use mirror.fsf.org in addition to repo.pureos.net in your apt sources.list so both repos will be used by apt for installing packages. This can speed up your downloads, especially when repo.puri.sm is heavily loaded, like when there is a new release and everyone is doing a dist-upgrade.
Create /etc/apt/mirrors.txt with these two lines,
https://repo.pureos.net/pureos
https://mirror.fsf.org/pureos
and update your sources.list like this,
deb mirror+file:/etc/apt/mirrors.txt dawn main
Today I was upgrading from crimson to dawn (this is still not officially supported, so do it only if you can figure things out yourself) and noticed repo.pureos.net was slow, so I looked around for another mirror and found mirror.fsf.org/pureos.
I am sharing it here so it is useful to more people.