Ethernet Cable or Not?

In either case Wi-Fi or Ethernet you deliver exactly the same data.  Wi-Fi might have advantage here, separating electrically noisy computer from the DAC, but the question is what happens with the received Wi-Fi data?  When your receiver converts it to S/Pdif serial stream adding timing it also adds jitter (instability of this timing), that might affect timing of the D/A converter (that is often based on the timing of the incoming stream) resulting in basically added noise (jitter=noise).   Coax, that you mentioned might also add to timing instability (affecting shape of transitions).  I don't know how jittery is output of your receiver or how sensitive to jitter is your DAC.  My Wi-Fi receiver (Airport Express) produces small amount of jitter (280ps) but my DAC (Benchmark DAC3) is jitter suppressing.  It seems that Ethernet or USB might be better since DAC clock is independent of incoming data timing, but they tend to, as Al mentioned, inject electrical noise into the DAC, indirectly inducing timing instability of D/A conversions (noisy clock=jitter).  I use WiFi (5GHz) across the room because I don't have any way to run Ethernet cable.  If both sound the same to you - go with Ethernet to avoid possible signal dropouts.  Get shielded Ethernet cable.  If you decide to go with Wi-Fi get dual band router and 5GHz receiver if possible.  Lower band has only 3 independent channels, since each channel is almost 4 channels wide.  5GHz has more channels and less traffic.

 Hi lalitk: Or here  https://www.ebay.com/itm/Supra-CAT-8-ETHERNET-cable-3-meter-Made-In-Sweden-THE-BEST-FOR-NETWORK-AUDI...
 I also highly recommend the linear power supply option as david_ten suggests.

Thanks for your feedback, I’ll check out these options. 

Hope everybody has a great weekend!

If you go the Linear Power Supply route, I encourage you to consider a LPS that offers multiple power outputs.

You did not specify your ’router’ (I’m assuming it is both a modem and router)... it is likely also DC powered.

A LPS, when used to power BOTH the ’router’ and your "WiFi Receiver" (Tunebox), will only add to the upsides with respect to performance and sound quality!

It appears your ’router’ is near enough (7 ft) to allow for one LPS to power both ’components.’ If not, and you like what a single LPS does for your system (with the Tunebox), simply add a second LPS to power your ’router’ at a later date.

All the best. Report back on the route you choose and the results.

Additional clarifying points.

1. You are already isolating your ’router’ from your "WiFi receiver" by using WiFi. This is a good thing.

In this scenario, a single LPS to your "WiFi receiver" is a good first step.

2. IF you choose to run ’wire,’ i.e. the LAN cable from your ’router’ to the "WiFi receiver"....

Then, powering your ’router’ with an LPS becomes more critical...for the reasons @almarg highlighted in his post.

Having a LPS that can power both is ideal and also allows you to test cable vs WiFi (to determine which one you prefer).