I have tried all of the things you have suggested and yesterday after spending nearly all yesterday on it trying to get it to work I gave up and went for a Chinese!
Let me give a bit of history. We are very nearly at the end of quite a large building works in BigBill Towers and I am going to move most of the kit into my office, just the things like the Unity, TV, DVD recorder etc will be in living rooms (plus a Muso or Qb haven't made my mind up yet). So I decided to treat myself to a new switch for my office, as you do and I purchased a Zyxel 24 port managed switch (GS1920 range). This is an amazing piece of kit for the money, I just couldn't believe what you can get these days for just over £100. I digress.
So I installed my new switch, played about with it a bit, then went downstairs to play a little music and it was then that I noticed the 'No Time' message and also found that it would not connect to my iPad. So I played a lot more and I could get rid of the 'No Time' message but it would still not connect. The symptoms were highly confusing, as I said in my original post the streamer was obviously connecting to my music server (QNAP/minim) because I could play music using the front panel controls and I could drive it from the UPnP controller option in FooBar from my main wokhorse win10 PC. I could ping it from my PC but when I checked on my iPad I couldn't ping it. So not surprisingly I suspected the new switch and was 95.76% sure that when I went back to the cheapo un-managed 8-porter it would work OK but it didn't!
Now the main cost to us while said building work is due to the fact that for quite some time all we could cook on was a gas camping burner and a microwave oven, unless we cooked in our motorhome; so we have been eating out a LOT and last night was no exception. We decided to go to our favourite Chinese and we usually get there by bus so myself and Mrs BigBill can both have a sherbert or two. So I reconnected into my new switch, shut down my QNAP server, which has minim on it and went to my iPad to get the bus times and would you believe it when I opened the damn thing up it was sat there connected to my Uniti, couldn't see my server of course, but it was connecting to the Uniti, something I hadn't been able to do all day! But when we got back from our Chinese feast and after powering up the server it wouldn't connect again.
But today I have found the problem. I have a number of very long ethernet 'hookup' cable and so I just networked: Uniti, QNAP, Switch and WiFi hub/WAN (ie for internet) with these cables and it all worked OK. Now I know what you are going to say:- "You should have done that in the first place, most network problems come down to faulty wiring." Ironically the wiring for ethernet and WAN/Voice are all going to be redone this week and so it looks like I just wasted a load of time Saturday!
But on the plus side I did really enjoy playing with my new switch, I might buy a second (or more) unit for the living rooms so I can fire 4 Gig from switch to switch and then shell out 1 Gig to my devices. I did say to Mrs BiggBill "Look how beautiful my new black box looks dear, wouldn't you like them downstairs in living room etc". I won't quote her reply!
Seriously though I thank all of you for replying to my early post and remember that on average over 60% of network problems are caused by wiring! Although if I am to be honest that little ditty may date back to the coax days and any of you old enough to remember that will know how rubbish it was.
Cheers guys