Yes, that’s my Mac. I saw this too. Therefore I opened UCP and also TCP port 9200 without success. Afterwards I switched off the whole firewall temporarily without success.
Now I try to enter the rules for 9200 and reboot the whole server … I let you know.
You may also want to check the Qnap settings to see if you have any restrictions there.(control panel - system - security)
Here is only the link to QNAP Firewall …
Now I rebooted with the new Firewall rules, which opens 9200/UDP and 9200/TCP.
The result is the same … no success → see log below.
10/30 18:13:17 Trace: [remoting/brokerserver] [initconn 192.168.42.152:55521=>192.168.42.42:9332] Connected
10/30 18:13:17 Warn: [remoting/brokerserver] [initconn 192.168.42.152:55521=>192.168.42.42:9332] failed: System.Exception: got unexpected broker id in REQ_HANDSHAKE: 0b68bf2e-db31-4a76-8513-e2edfe6f3665
at Sooloos.Broker.Distributed.InitConnectionV2.Go()
10/30 18:13:17 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] lost client connection. Retrying
10/30 18:13:17 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connecting (attempt 1)
10/30 18:13:17 Info: [transport] destroyed zone MacPro System was playing? False
10/30 18:13:17 Trace: [zone MacPro System] Suspend
10/30 18:13:17 Info: [zone MacPro System] Canceling Pending Sleep
10/30 18:13:17 Info: [zone MacPro System] Canceling Pending Sleep
10/30 18:13:17 Warn: [rnet/RnetJsonClient] failed to connect Connection refused
10/30 18:13:17 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] client connection failed. Retrying in 500ms
10/30 18:13:18 Info: [stats] 21294mb Virtual, 1566mb Physical, 1132mb Managed, 395 Handles, 120 Threads
10/30 18:13:18 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connecting (attempt 2)
10/30 18:13:18 Warn: [rnet/RnetJsonClient] failed to connect Connection refused
10/30 18:13:18 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] client connection failed. Retrying in 750ms
10/30 18:13:19 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connecting (attempt 3)
10/30 18:13:19 Warn: [rnet/RnetJsonClient] failed to connect Connection refused
10/30 18:13:19 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] client connection failed. Retrying in 1125ms
10/30 18:13:19 Debug: [history] loading history for d658dc74-5a31-4178-8370-de63f8ceee63
10/30 18:13:19 Trace: [history] Loading plays
10/30 18:13:19 Trace: [history] loaded 0 plays, 0 have tracks, 0 lib plays, 0 non-lib plays
10/30 18:13:19 Trace: [history] history loaded in 0ms
you have QuFirewall on the Qnap?
Stop it and try again
I switched off the QuFirewall on the QNAP, restarted the Roon server, but without success.
I get the same messages in the log file:
10/30 18:57:14 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] lost client connection. Retrying
10/30 18:57:14 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connecting (attempt 1)
10/30 18:57:14 Warn: [raat_ll/client] [System Output] failed to connect Cannot access a disposed object.
Replaced the cable between nas and MacBook?
well, there’s something blocking this. Either qnap, router or MacBook. You just need to find what that is.
how is your MacBook connected? To the router via Ethernet?
But here:
10/30 18:57:44 Info: [raatserver] GOT SERVER 47f05574-b043-4580-af45-a4799c1aa284::71669afa-1573-446b-8dd7-181c53bf8a4a @ 192.168.42.152:9200 MacBook-Pro-von-Michael-2 PROTOVER=1 RAATVER=1.1.39
10/30 18:57:44 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connecting (attempt 1)
10/30 18:57:44 Trace: [raatserver] [RaatServer MacBook-Pro-von-Michael-2 @ 192.168.42.152:9200] connected
it connected, but with the same error on Roon side “Too many failures…”
AND 192.168.42.152 is my Mac NOT my QNAP. That means that the port 9200 on my MAC is the problem. Right?
My MacBook Pro is connected via WLAN, but my DAC Unity Nova is connected via LAN and on both devices I get the error playing music on Roon.
Now I opened also the port 9200 on the router with the same error message … 
I don’t know. Since ARC is working ok, access from your WAN to Qnap is OK. That indicates that while enabling that, somehow access to/from your Lan to Qnap got messed up.Can you browse \ copy files on your qnap from your MacBook?
you don’t need to open that port on the WAN, but you should not block it on the LAN/WLAN side.
Thank you for your time kc1.
Yes, I can browse / copy files from MacBook to QNAP and the other way round.
I’m not blocking internal network traffic with my router …
I’m totally frustrated …
Does anyone know which protocol is used by Roon to read the music files? Can the problem be caused by this access?
what is interesting is that you can connect to/from port 53003 but not 9200 …
Headache of a problem 
Port 9200 is RAATServer. A TCP port.
To list all the active listening ports on a unix box, use netstat in a terminal window:
$ sudo netstat -tlp
It should show you both the port number (in the column labelled “Local Address”) and the program’s name (in the column labelled “PID/Program name”).
I don’t have a Mac, just a linux box running Roon Bridge, and I see this line:
tcp 0 0 0.0.0.0:9200 0.0.0.0:* LISTEN 1641/RAATServer
In my experience, “Connection refused” usually means that no program is listening on that port.
How can I involve the Roon Support guys? I thought in this “Support” group are they …
I haven’t really taken a look at the logs you posted, but the sequence of symptoms would suggest to me that your MacBook (or one of your other endpoints) is going on and off the network.
Thank you very much for your thoughts …
I tried another Wifi network access point with the same result. … and also my Unity Nova DAC, which is connected via LAN, does not work (error “Too many failures …”).
Also I connected my Mac via Ethernet / LAN to the network with the same result.
OK, this says your MacBook (42.152) is attempting to connect a different computer (42.42), which is presumably your Core machine. The connection apparently succeeds.
There’s some handshake here involving a token, which returns the wrong token. Odd failure; I’ve never seen this. Could you be running two different versions of the software? One version on the Core machine, a different version on the Mac?
The Core can’t connect to the MacBook.
