Syncing files with a big document library

David_Elsner 

"What could we do about that?"
Short answer: not much

Long answer:
The OneDrive for Business client has a limit of 300000 items and using Files on-demand capability will not change that. Throwing bandwidth into the mix also will not help.
Splitting your content across multiple libraries will also not help. They all count towards the 300000 item limit.

Use Internet Explorer to enable users to start "View in File Explorer" is not a long-term option because IE support will end 17 August 2021.

Synching files to different clients may expose your content (e.g. stolen laptop with corporate data)

Options:
1. keep the files on a network drive
This may pose problems in terms of accessibility, managing permissions, lack of search, ...

2. Adopt a new way of working

3. Use client side tools to access SharePoint (e.g. standard WebClient in Windows)

4. Use commercial apps that mimic File Explorer in a browser.

Paul