Q: iTunes won't start when connected to network without internet

Everything is up to date. I have also turned it off and on.

Any actual advice?

Seems obvious that it's trying to phone home. How can I tell it not to?

Partial fix, under iTunes Preferences,

General > Look for Automatically retrieve CD Track Names from Internet (Disable This)

Sharing > Un-check ALL

Store > Un-check Music, TV shows, Movies, Apps, Always check for available DLs, Sync Playback Info..., Sync Podcasts.., Auto DL Album Art, and Share Details with Apple.

Restrictions > Check to Disable Podcasts, Internet Radio, iTunes Store, Allow access to i tunes U, Apple Music, Connect, Shared Libraries.

Advanced > Un-check Check for new software updates automatically.

That's an improvement. Still beachballs for almost exactly a minute, which can be forever when something unexpected happens and the presenter says "Put some music on."