When you're working offline because you have a slow connection, you can temporarily switch to working online. To do this, ...

When you're working offline because you have a slow connection, you can temporarily switch to working online. To do this, open File Explorer, choose "Home", "Easy access", and then "Work offline".

After the amount of time specified here, Windows checks your connection speed. If it's slow or you're set to always work offline, Windows switches you back to working offline.