This is my first (semi-) prebuilt NAS and setting this up in the way I want is proving to be more complicated than I thought (more complicated than the LTT video conveyed that it would be).

I have a new FS6706T with 6x4TB drives, in RAID 6. Ideally, this NAS would be able to act as an "archive" that can do its job while with only wired connections, a connection between the NAS and the client. Everything else is mostly a bonus.

Setup/initialization went mostly smoothly, save for registration. I downloaded the most recent ADM (4.2.7.RRD1) and used that for the setup. All was well until I got to registration, where I got an infinite loading screen.

As it stands now:

I can access the NAS via the web portal and fiddle with things, the synchronization went perfectly, I can add stuff to the NAS via its own file manager, and ACC recognizes it just fine.

But, the NAS only seldom shows up in the Windows File Manager and when it does, Windows can't access it because it doesn't actually exist, and the NAS itself can't seem to connect to the internet. Can't check for system updates, the App Center shows nothing, etc. If it has to do with Windows' file manager, it don't work.

Are my expectations for how this NAS can be used reasonable? If so, how can they be achieved?

I don't know what information you need; tell me and I will do my best to provide. Note that I am not experienced in network-related stuff.