Back in the old days, we had workstations. And only workstations. They lived on a network, and having them work in that network was simple. Printers just worked (thank you printcap), network shares just worked (thank you NFS) and life was good.
Then along came laptops. We wanted to be more mobile, using our laptops on different networks or even without a network! No one wanted hardcoded printers anymore, or network shares defined in /etc/fstab. Using an Automounter was an option, but if you were on a different network then having the Automounter around would stall tools like nautilus and file indexers etc.
So we need something which can start up relevant services when you connect to a network, and then stop them when you leave that network.
To support this, a few years ago I wrote a NetworkManager dispatcher.d script to do just that. When you connect to a specific network (using the NetworkManager UUID or a specific gateway MAC) or a VPN connection then autofs is started, users GTK bookmarks have any bookmarks for their Network shares added and CUPS is restarted.
When the connection goes away, then autofs is stopped, any GTK bookmarks for the Network shares are removed and any mounts for the Network shares are lazily unmounted.