Enable/Disable application-specific settings (updates, upload) for a specific WiFi
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

&nbsp;&nbsp;&nbsp;&nbsp;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)
&nbsp;&nbsp;&nbsp;&nbsp;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)

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