Network Switches

Looks like the the iFi LAN ipurifier pro and the effe unit both run the signal through a transmitter, a receiver, and a short length of fiber. This works well, and it is essentially the exact same setup @deep_333 described in one of his posts above, except all components are integrated in a single box, which is more convenient and less unwieldy. It also costs $299 instead of $40ish.

Also, discrete components let you have any length fiber run you need, handy if you keep your Internet gear in a separate room.

I tried the copper to fiber two box solution using a $65 set from amazon. I tested these with 3 different streamers and I did not like the effect. Yes it seems to produce a more silent background but it imparts a certain flavor to the presentation especially obvious in the mids that renders it unnatural. I made several attempts and each time yanked it out and went back to straight copper cable between eero and streamer. Streamers used: Lumin U1 Mini, Bricasti M3 DAC network renderer, Aurender N200.  
I am keeping an open mind and will try the iFi pro purifier when I have an opportunity but I’m not in a hurry to do it. 

As to effe-01….I’d love to try it but trying something shipped from Europe is not very appealing to me as the return shipping is a pain in the 🫏 

You guys can try it and let me know. I’ll be patiently waiting. 

Pardon my ignorance, but what is the effe - 01 and how does this fit into the above recommendations

Effe-01 is an optical network isolator. Not exactly a switch but you are not asking about a switch because you need to branch out to many devices. You’re asking for something that can improve your network. There are many ways to skin this CAT. 
Optical isolation, switch with reclocker/regen, passive filters like the NA Eno, etc