Connecting Bluesound Node 2i Questions

I think that's true. Coax must maintain proper impedance, grounding, and jitter control.

I’ve seen optical toslink switches, I don’t think jitter is much of a problem with optical.

https://www.amazon.com/Portta-Digital-Optical-Switcher-Toslink/dp/B01A89OEUY

My first issue is I already have the Coaxial RCA & TOSLINK digital optical inputs in use on the DAC (from other sources I would like to maintain) is there a splitter or Y cable solution for either the Coaxial RCA & TOSLINK lines into the DAC?

This is an interesting question and one that I can relate to. Using 2 digital sources into a Y-cable or a switch box seems like a solution, but 75 ohms impedance must be maintained for S/PDIF coax. Another issue is adding a switching device or splitter may change the asynchronous signal and add jitter before it enters the DAC.
So I’m looking for an answer as well.

I wouldn’t recommend the power line Ethernet connection as it’s probably the noisiest option.  The best from a sound quality perspective would likely be to run an additional cable from the router to the Node 2i.  No idea about splitter options. 

Why not operate wireless?  I have a Node 2i and Pulse Flex 2i, and both perform flawlessly wireless.

Hello Mark.
Don't think you can go wrong with a Bluesound Node 2i.  I currently have 4 pieces of Bluesound kit in the house, including a Node 2i.  I've been using them since 2014 beginning with the original Node N100.

With respect to your need for one more digital input:
As it so happens, the Node 2i has a digital input. I don't know if digital input is passed through to the digital outputs.  If so, then your problem is solved.  If not, then worst case is you can use the Node's internal DAC for one of your digital sources. Otherwise you'd have to purchase either a switch or splitter.  I didn't see anything in the Node owner's manual.  So you would either need to experiment, or perhaps better yet, put the question to the Bluesound folk over at bluesound.com.

With respect to providing a wired streaming signal,
here are some ways of providing an ethernet port without having to cut holes in the wall or fish cable:
- Establish a wifi mesh network. And then use rj45 port on mesh network hardware to establish ethernet connection for your main system. Could consider wifi mesh extender that could be used with existing router.
(estimated cost for hardware $150-$300)
- Utilize pair of powerline ethernet adaptors. This is a relatively inexpensive option. (less than $100 for hardware).
I myself was faced with the same problem when I got seriously into streaming back in 2014. My Gateway (combo modem and router) is on my lower level. My main rig is on the main level. I went the powerline ethernet route back in 2014 which I'm still using. I have been considering upgrading to a mesh network solution using a wifi mesh extender.