Tasker can indeed do what you are looking for! Using the Wifi-Connected State profile inverted (profile on when not connected) you can trigger a task that does the following:

1. Disable Google Play updates via Synker

2. Stop auto-upload of photos using Dropsync (replaces Dropbox built-in tool)

3. Use Secure Settings to connect to stored VPN (requires root)

Tasker can indeed do what you are looking for! Using the Wifi-Connected State profile inverted (profile on when not connected) you can trigger a task that does the following:

1. Disable Google Play updates via Synker

     In newly created task Add an Action ('+' at bottom, center of screen), select 'Plugin' category, select Synker, select 'Autosync Settings', select Configuration, uncheck the Google /account name/ App Data)     Source: Is there an App Update Scheduler app? Reply #6

2. Stop auto-upload of photos using Dropsync (replaces Dropbox built-in tool)

3. Use Secure Settings to connect to stored VPN (requires root)

     In newly created task Add an Action (new Action> Plugins> Secure Settings> Root Actions> VPN)     Source: VPN Verbindung (keine Zusatzapp) per Tasker starten?