This drove me crazy, since I was able to go into File Explorer and see most of my files on my ChromeBox, my windows 10 PC crashed I did a fresh install of Windows, and could not get back into File Explorer read thread after thread and all the post that actually did not help, YES I know samba 1 is NG, this does not stop the fact that many users are in the dark.
OK, how to fix, in LibreElec>>Programs>>LibreElec>>Services>>Minimum supported protocol>>>SMB1 & Maximum supported protocol>>>SMB1
Now on your Windows PC, Open Control Panel click Programs, and then click Turn Windows features on or off (under the Programs heading). Check the check box for SMB 1.0/CIFS File Sharing Support, You should now be able to open File Explorer, type \\YOUR.KODI.BOX.IP.ADDRESS\
and see all the heavenly glory.
As stated before doing so is not safe from the CIA, FBI and NSA, along with the many unscrupulous folks out there. So beware.