Audio Grade Ethernet Cable

@cleeds Didn't know that thank you.

@ghdprentice I have the wall wart for the modem and the router LPS cable plugged into a passive line conditioner but it's close to the stereo. I'll try running those to a bare receptacle on the other side of the room. The modem/router are currently 10 feet from the streamer. I'll see if I can move it further.

My local files sound great which is why I've been investing in downloads. From what others have posted on Audiogon, the Bryston BDP 3 is a very good sounding transport. There were complaints about the software which is why those Goners purchased different streamers (which Bryston is in. the process of improving).

Is this a waste of time and money?

Yes.  CAT(5, 6,......) specs are tighter than what any boutique cable builder can achieve.  Just buy good quality name brand stuff.

@kr4 Can you send me  a link? I was told to use a CAT 8 cable so I bought one, then I read that a CAT 8 cable carries too much noise. I'd at least like to have a solid understanding of the basics. Thanks!

Ten feet is probably far enough. Hopefully the wall warts are not plugged in to the same circuit as your audio stuff. I am not completely sure a line conditioner will prevent degradation of sound if they are. 

Stored files should not sound any better than streaming. If same recording, my CD = Stored files = streaming = vinyl. It is worth getting streaming = other since your library goes up to millions of albums for the price of $14 / month.

That will slowly change everything in a really good way. Not just relistinging to the same music but finding hundreds of new and great music. I seldom listen to anything that is in my 4,000 CD / Vinyl collection. And my outlays for music are a flat $14 / month. I’m retired so having all that music is incredibly wonderful. I’m listening to five Cannonball Adderly album’s I never heard before. It’s incredible. 

The opposite - you should get your router as far away as possible from your components. Routers emit noise. 
Ethernet cables make a difference. I’ve tested several and they all sounded different. I tried Supra, Supra with Telegartner connectors, LinkUp from Amazon (very decent by the way), Purist Audio and Audience (mu current cable). 

DH Labs cables are excellent value and they’re a good entry point into higher quality cables. If you want to go cheap get Linkup. 
https://a.co/d/elkT0FX

Then save up and upgrade to something in the $500-$1000 category.