A friend of mine spent weeks with the same problem, tried everything he could. His son came home from flight school and in 20 minutes had it working. Neither one knew exactly what was wrong. 
I had the same problem for a couple of days, so I turned everything off, unplugged everything, rehooked, and then it worked.
Hi OzarkTom,
Very strange - I never ran into this problem yet on my unit or any of the ones I modded already. Maybe it has to do with how it talks to a particular make/model of router?

Hi Afterimage,
You might also want to reset your wifi router and see if that also helps. But
good to know you aren't the only one...
As for the sound, it is fantastic!!! Warm, spacious, organic. And the bass is the best I have heard from a source.
Glad you are enjoying it - even with low hours on the mods! Please keep us posted, and we'd all love to hear how it compares to what you
have been using before it. Spill the beans!

Hi bmoura,
Sorry I couldn't make Newport Beach this year. Next up for me is Capital Audio Fest, then NY Audio Show, and then RMAF...
I'm sure people at the show are finding out that it is a great product for the money. I'm sure they are selling way more than they thought they
would. The reviews in the big magazines have been hot, the forum chatter has been hot, and the mod potential on them to get a player with such capabilities that can go head-to-head with pricer competition makes for a "product of the year" candidate in my book!
I hope some of my other customers who should have received their modded units last week are enjoying them and will post their impressions. If you are not signed up to post, please do so and share your RWA-Z1ES experiences, and thank you.
Happy listening, everyone!
Vinnie