Hello @Andrew_Schau
First, an apology: we referred to a Ubiquiti Dream Router and sent you a guide for it. That was our mistake, it is not your equipment, and you can ignore that link entirely.
Second, please do not worry about the terminology. You do not need to understand any of it. What you have told us is actually enough to narrow this down a lot, and the fix is likely to be simple.
Here is the plain version of the problem. Your eero hands out addresses that begin with 192.168.4, which is why your NAS is 192.168.4.39 and your eero itself is 192.168.4.1. Your Nucleus has an address beginning with 192.168.5, which your eero does not hand out at all. So something other than your eero is giving the Nucleus its address, and that something is keeping it on a separate network from everything else.
Nine times out of ten this is an extra piece of equipment still sitting in the chain. Very often it is an older router that was never removed, and which is still acting as a router rather than just passing the signal along. It would not look like a second network to you. It would just look like a box.
So the one thing we need from you is this: please follow the network cable out of the back of your Nucleus and tell us what it plugs into. Then follow the cable out of that, and tell us what that plugs into, and keep going until you reach the eero. A photo of each box is fine if you would rather not identify them, and the brand name and model printed on the front is even better.
While you are at it, please do the same for your NAS. Knowing whether the NAS and the Nucleus plug into the same box or into different ones will tell us a great deal.
Please open the Nucleus web page in a browser. Since yours is a Nucleus Titan, the address is:
http://nucleustitan.local
If that does not load, try http://nucleustitan on its own, or the address Roon shows for the Nucleus, http://192.168.5.78. Please send us a screenshot of the whole page, including the network section. We want to see whether the network setting is on automatic or whether a fixed address was entered at some point, and what the subnet mask says.
One reminder from before, since it still matters: please do not remove the existing NAS entry in Roon’s Storage settings, even though it shows as unavailable. Your playlists, tags and play history are attached to it. Once the addresses are sorted it will reconnect on its own.
