Mistake to change from Spectrum (Coaxial) to Fios (Fiber optical)???

Auralic is just a streamer? You have external DAC?

Potentially some incompatibility between the Auralic and your what I assume is your new Modem/Router?  If a new Modem/Router, since you have it hard wired, and throw in a DAC there, there could be some electrical issue and that seems more likely.

When you have digital streaming issues, you have drop-outs. You don't lose bass and you shouldn't have sound-stage issues unless your Auralic is doing something strange. 

Do a speed test so you know if you are as fast as your prior connection is. When I went from 25mbs ATT DSL to 300 mbs ATT fiber, sound got better. When I move to 1 gbs ATT fiber sound improved a bit more for sure. I have no experience with Spectrum. But I can say that moving from DSL over a telephone wire to fiber is better. In my area, you get much more speed for your money versus Spectrum.

To follow up, I changed back to (Spectrum) "Coaxial cable" a few days ago. Note: I'm referring to the cable that runs from the street utility pole to house/ modem. Verizon Fios use a fiber optic, ( I overlooked this when I changed cable companies). Increasing the internet speed of the fiber optic did improve the sound but still not as good as coax.
There is audible difference between the two cables, I find the coaxial delivers a superior sound to fiber optical. I stream Tidal.
An audible difference is evident on my Martin Logan Montis speakers and more so on my Raidho D3's. Noticeable differences such as a finger snap to plucking a guitar, depth of piano etc.