Thanks all.
sns - I do not have a server, if I purchase a bundle from SGC the Sonictransporter i5 would be my music server.
My current router is a combo router/modem, an older Netgear AC1750 so the only reason I presume I would need a switch would be for a optical line for the Rendu.
There hasn't been much emphasis on modems in most of these "Digital" conversations. My older Netgear AC1750 works great but should I consider upgrading it? It has been discontinued so this is the only this is the only link I could find for it:
https://www.staples.com/NETGEAR-AC1750-Wi-Fi-Cable-Modem-Router-C6300/product_822201