Mike, did you mean system hibernation? If so, yeah, probably a good idea to try turning that off. If its HDD hibernation though, it shouldn’t affect your UPnP Server functioning properly, you don’t need to turn that off.
What UPnP Server are you using on the Synology?
Anupc, my synology NAS is using media server as its UPnP player. i poked around in it and didnt understand alot of the settings, i did come across a setting to shorten advertisments if having trouble connecting to a device i changed it from 940 to 800. still had the error again this morning. i did turn off all hibernation modes. i think i need more help with setup of the media server, i will research it on the web.
i am a punch card kinda computer person so Dnla etc. makes no sense to me.
cheers
mike
You should install MinimServer on the Synology NAS. It’s what dCS recommends you use as a media server; and it’s very easy to do from the Package Center.
Mike, as Paul suggests, it’s not a bad idea to switch to MinimServer for full compatibility sake.
That said, Synology’s Media Server is pretty rudimentary and should work. If the Bartok is unable to see it after a couple of hours, something else might still be going wrong on your network.
I’ve got a Synology NAS as well (which I don’t normally use for any UPnP Services). I just installed Media Server on it with its default configuration. So far it’s always responded to my Mosaic queries (on both my Bartok and Vivaldi). I’ll let it run for couple of days and see how it operates.
In the mean time, one questions and one suggestion;
What’s the brand/model of your main Router? Just wondering if it’s doing something funky. Your Netgear GS108v4 Switch is a very basic unmanaged Switch, it can’t be doing anything wrong.
When next you have an error accessing the UPnP Server from Mosaic, don’t do anything else just try the following;
If the Bartok does show up on the list, try Mosaic again and see if you still get an error. If theres no error this time, then the problem is likely something to do with the Synology/Media Server. If the Bartok is not on that list though, then there’s likely a network problem somewhere.
Anupc i installed MinimServer last night prior to reading your latest reply had to turn off Media Server and reboot the NAS to get it to work. after it installed the Bartok saw it and played music from my music folder with no issues, this morning i get the error message again, so i go upstairs and get the make and model of my Router its a TP-Link AC1750, about a year old. i also think i found out why i lose the Connection nightly i forgot i put a timer on the router and incoming radio, to shut off for 30 minutes nightly. (when i have internet issues thats the first thing my provider has me do) , So now i no why the signal is getting disconnected now i still need to figure out why the Bartok doesnt reconnect to the UPnP server, my oppo which is connected to the same switch sees the UPnP while the Bartok doesnt until i reboot it.
thanks
MIke
Mike, actually, UPnP/DNLA doesn’t operate with a permanent “connection” between the Server and Renderer (or Control point). The way it works is that the Server and the Renderer (Bartok) will discover each other by independently advertising its availability over the network via an IP multicast packet every so often (thats the “SSDP advertisement interval” configuration on the Synology Media Server - it advertises itself every 15mins by default), and then acknowledging the other.
If the nightly power shut-off fix doesn’t solve the problem, I’d suggests the same as for Erwin (though technically it shouldn’t be impacting your setup 
).
Pull down the User Manual for the TP-Link AC1750, if you don’t already have it handy.
Access the Router’s configuration Web UI, should be at its default LAN address of 192.168.0.1. Make sure to Disable both IGMP Snooping and IGMP Proxy (described at the bottom of Page 76, and on page 77).
Hopefully that addresses the issue. Can’t imagine what else could be going wrong 
One of the unfortunate problems with UPnP/DLNA; it doesn’t always work the same across various vendor implementations. 
Hi Anupc, my apologies for this late reply. I have been observing my Bartok-server connection for the past several days.
After I turned off the UPnP, DLNA, and IGMP in my router, the Bartok still shows “no UPnP servers available”. I rebooted the Bartok and it worked for about 24 hrs and eventually disconnected again. Finally, I changed my switch to Linksys SE2500 and so far it has been working (a little over 24 hrs). I’ll continue to observe and update you, and Mike!
Although the Linksys SE2500 is a basic unmanaged switch, I don’t know if my previous switch, Nighthawk AC1900 WiFi Extender EX7000, is a managed one (difference?).
Excellent, sounds like you’ve solved the issue! 
The real issue is whether or not a Switch filters out specific IP Multicast packets necessary for the dCS component and the UPnP server to discover and exchange service information with each other.
Unmanaged switches are typically dumb and just pass all traffic through without interfering. Managed switches work fine too as long as they’re configurable to not filter out those multicast packets.
Your EX7000 is a Managed switch, but has no configuration for handling those multicast packets. So the presumption was that it doesn’t interfere (which apparently seems wrong).
Incidentally, there exist Unmanaged switches that don’t behave properly either, so it’s not just misconfigured Managed switches that could problematic 
I bought an Ansuz switch connected to Melco w/ upnp yesterday. Switching it on now I have same problem, message „upnp server not found“. Cisco 2960 worked…any idea folks?
Many many thanks!
I assume that your Melco is being used as NAS and that the UPnP server installed is MinimServer or Minim Server 2. If so Melco connects directly to your dCS network device so no switch is involved for serving files via UPnP (Mosaic commands still go via the switch of course). A switch ( between router or Modem and Melco ) would mainly relate to internet sources or external music servers such as a computer or phone which route via the switch.
Perhaps you would kindly clarify how your Ansuz switch/Melco/dCS device are physically configured?
Once known we may also consider other matters such as the Melco configuration and if the IP address of it is "known " by Mosaic. Of you run MinimServer on Melco do you also have MinimWatch installed on a computer as that may help?
Thank you Par,
Melco, wlan repeater, dCS and roon server are connected through Ansuz.
Strange: roon sees melco and I‘m able to play music. dCS Mosaic doesn‘t see upnp server.
Add on: melco has usb connection to dCS as well and I see this as upnp server with kazoo/linn app!
Rebooted dCS- all upnp serers are there again….
Melco and dCS should ideally not be connected through Ansuz switch. Please see Melco user manual. As I am not a Roon user I imagine that there might be a difference to this ideal configuration.
I think what may have happened is that you have been using a dynamic IP address for Melco and when you added the Ansuz switch your router allocated an new IP address to the Melco. You should be able to look at the Melco and its contents via your computer. The Melco will display its current IP address on its home screen. Type two back slashes, dot and the number e.g. 192.168.xxx.xx into the search bar on your OS file explorer. If you have a currently viable IP address you should see Melco and its contents. If it is not recognised then you need to reset the IP address ( don’t ask me ). Despite dCS’ advice about dynamic addresses, when using Melco it is more reliable using a static address. How to set this is also shown in the user manual.
However all now seems well.
Many thanks!
I try to fix the IP@ issue now by skipping dhcp!
Great, just a couple of amendments. When looking at Melco on your computer forget typing a dot after the back slashes when when entering the Melco’s IP address in the search bar ( that’s me trying to do things from memory 
). You also need to visit “settings” on the Melco and enable " SMB file sharing".
Thanks Pete,
I can see the melco and have access to the files there. Roon server sees melco and the content there as well (over SMB)
Next step is to change router settings so, that melco, dcs and roon server will “always assign same IP@”.
doesn’t work…changed settings to “always assign same IP@” but dCS doesn’t detect upnp server. After switching off dCS they are there again. Since I only changed the switch (Cisco out, Ansuz in) it seems that dCS has issue with this so if anyone here has an Ansuz feedback would be highly appreciated! 
While I think it’s generally a good idea to have fixed IP addresses for UPnP Servers and the dCS kit, it’s not necessary.
This is because the way Mosaic (currently) initiates any dialog to the UPnP Server is by sending out a multicast service discovery request (SSDP), every time. It doesn’t rely on “remembering” the IP address of your UPnP Server, so having a fixed IP address isn’t necessary. So, all the discussion about DHCP is quite irrelevant. 
This also means that your home network has to have multicast operating properly; any glitches with multicast will result in the SSDP request or responses going missing, and you’ll end up with the symptoms you’re seeing.
Ansuz doesn’t make their manuals available online, I’d recommend you check the manual and figure out how to disable IGMP Proxy or any other multicast filtering that might be occurring with the switch.
The usual excellent advice from Anup.
Also check whether your Melco is set to use a fixed address or automatically from DHCP:
Settings/Network/LAN Port/ then select DHCP or Fixed IP and enter using the menu/enter button.
Oops, just realised that that Ansuz Ethernet Switch is in fact a modded D-Link DGS-108 - an unmanaged switch, but has IGMP Snooping that apparently can’t be turned off.
I’d return that switch and put the Cisco back in 
Ansuz Switch;
D-Link DGS-108 (modded pic);
