Problem with Active Domain GPO settings, unable to join shared folder.

Question

So basically I have my own active domain I have complete control over. I want to make this very clear because every fix I find to this issue on the internet is talking about enabling insecure guest logons, which is not something I want to do.

Here is the setup:

A Samba Active Directory Domain Controller running on an Ubuntu server.

A Samba file share server hosting a shared folder running on an Ubuntu server.

A Windows 10 workstation with RSAT tools on the same network.

Here is the error:

It says that there are group policy settings restricting "unauthenticated guest access". The reason why I find this error so strange is that I am logged in with the Administrator account of the domain. On top of this, there is nothing in the file server configuration blocking guest access to begin with.

Below is a screenshot of the file server configuration. As you can see under the Share header, guest access is explicitly enabled, however I still don't understand why I would be flagged as a guest to begin with.

I have a couple of theories on how I could fix the issue.

1. Enable shared folder guest access

Although I said I don't want to enable insecure guest logons, I want to mention that since the error specifically mentions a "guest" who is unable to log in due to "group policy settings", I should be able to find the group policy setting somewhere! However I can't find it anywhere in the group policy editor.

2. Figure out why any user who is logged in and has access to the shared folder is flagged as guest

If I managed to find out what is causing the users, including the Administrator of the Active Domain, to be flagged as guests, then everything would be fine. Guests not being able to log in to the shared folder is a good thing in this case, however why would the authorized users also be flagged as guest?

Any help is greatly appreciated!EDIT:

After some fooling around trying to fix the issue, I believe I only made it worse. I created the file server again from scratch and although other things seem to be going well now, I am still facing the same issue with the unauthenticated guest acces.