My experience over the last 8 years or so is for CD resolution streaming, wifi need not be a problem as long as functioning properly and connections are strong(say >80%). That is with good quality gear designed to stream CD res audio or higher over wifi.
It is best if disk storage is physically connected to server (not remote on the network) and streaming occurs from wifi connected player to server only (again with a strong wifi connection).
Results will vary server by server still. Two software server programs I can recommend that do things well are Logitech MEdia Server ( though this is no longer undergoing active development and not a good choice for new users) and Plex Server, which I have started to phase in as a replacement for LMS.
I do not have any experience with current one box audio music server products ( I prefer running good software on commercial computers to buying proprietary hardware from specialized vendors) but I have read mixed results over the years with many and would be cautious and only consider newer products/technology that have received large scale acceptance and positive reviews. Sonos, Bluesound, Sony are three product lines I have seen that seem to be getting decent traction in B&M shops lately, with Sonos probably having the most users currently.