I inherited all four and they were 'self built'. Two are already using the EMBC learning platform and another is soon to be training on it.
One however - was only a peer-to-peer network when I took it on. Now they have a domain built from the ground up by yours truely.
Another I've pretty much managed to rebuild underneath itself.
The other two are still in a bit of a mess as they had several years of not being supported properly.