Adding NAS folder shortcuts to finder sidebar

Hi all -

I have a home (wired) network that has a QNAP 453 NAS on it, which i use for backup and storage and other things. I have no problems connecting to from my MBP (2015) either wired or wirelessly.

However, I have a few folders I'd like to permanently see in the finder sidebar, and I can't for the life of me figure out why I can't add them. I've already added them to the login items, but they don't appear in finder automatically. Further, when I try to grab one of the folders and drag it over to the "locations" sidebar, it doesn't stick.

You can see in the screenshot there are a few ways the NAS shows up: grossserv, grossserv(AFP), and I can also get to it through the "Network" in locations. These seem like they all point to the same place. (the duplicate "network" path makes sense to me, but I'm not sure what the AFP is all about...) Regardless, the issue is that whenever I try to drag one of the NAS folders to the "Locations" sidebar, it just doesn't stick.

This behavior persists whether I'm connected wired or wirelessly.

Any ideas what I'm doing wrong?

Thanks!

Geoff