No access to the C$ share with a local administrator due to the LocalAccountTokenFilterPolicy

By default, it is not possible to access c$ with a local administrator, which is not the default administrator user. This is caused by the local user account control setting (UAC) LocalAccountTokenFilterPolicy. When this setting is set to 0 then it is not possible to have the same rights as your default administrator user.

Change this setting with the following CMD command:

Or manually with regedit:

You need to add a new DWORD value in the registry.

Run -> Regedit
Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
Add a new DWORD Value called: LocalAccountTokenFilterPolicy and give it the value of 1.

Reboot the system.