Anybody gone from ethernet to optical for connection to a streamer?

Yes, it made a worthwhile improvement in my steaming setup. In my case I place optical between server and Usb renderer (Sotm sms 200 neo, powered by Uptone Js-2 lps). Use two TP Link MC200CM, both powered with LPS for the conversion.

Optical conversion galvanically isolates from ground noise on ethernet. Result, blacker background, higher resolution thing.

I've found optimizing streaming is complex undertaking, steaming setup much more complex than my analog. I used Audiophilesyle forums as my guide for setup, steaming now preferable to my pretty nice analog setup for sound quality.

Appreciate use of word renderer indescribing the streaming foodchain.

I have both (wired ethernet and fiber).  Fiber is clearly superior.

I have an Etheregen and tried it with both Fiber and CAT and I could not hear the difference. (yes, I had only one hooked up at a time).  The Etheregen switch claims it's "moat" galvanically separates the "in" from the "out". My limited listening test confirmed this in my opinion. That said, I don't know if this helps answer your question, but you might find it useful.  

I’m a little confused are you talking about a fiber connection from your modem/ router to a streamer. If so what type of modem? I’m in the telecom industry but not familiar with any modem that that has fiber outputs only a single input. What equipment is before the streamer?