Can't access user shares from freshly installed Windows machine - all other devices work

[The_Resident_Skeptic 0]

As per title. Everything works from multiple other devices, but this Windows machine is demanding permissions to access the shares on the network as if the password's wrong. I've tried changing the password, deleting the account from Windows Credentials Manager, running the permissions Tool, restarting the server and client machine. I have Windows 10 and no other software installed except Firefox. If I change the share to Public instead of Secure/Private I can access it. Um.... wut?

Edited February 12 by The_Resident_Skeptic