Lockdown SharePoint Onedrive access to certain IP / computers

Pn1995  the cleanest and simplest approach would be Conditional access policies but that will require you to have EMS licenses.

Without EMS you could try the following:

For the OneDrive Sync client: You could add a restriction to only allow syncing from machines that are joined to your AD Domain.

Note:With this approach, you either allow all Macs or Block All. And this does not affect Mobile devices.

https://docs.microsoft.com/en-us/onedrive/allow-syncing-only-on-specific-domains

For Browser based access: SharePoint Online does have a feature that lets you restrict access to particular IPs.

https://docs.microsoft.com/en-us/sharepoint/control-access-based-on-network-location