Serviio and Xbox One S Media Player

I've had Serviio running for some time on a Win10 computer that performs as a network NAS and various server functions. It's worked fine streaming to a Samsung Blu-Ray player and other devices. However, I've recently replaced the Samsung with an XBox One S for it's 4K playing ability, but it's Media Player app (which is up-to-date) does not see Serviio. Both are on the same subnet -- no intervening routers. Any suggestions?