I would try the following, to figure out if this is some conflict of Sooloos and Roon Server:
Stop temporarily Sooloos on the QNAP. Restart Roon Server and see if solves the problem.
According to this forum post Sooloos is using different ports than Roon Server.
Sooloos is using
- UDP port 9001, 9002, 9131
- TCP ports 9011, 9012, 9080
Roon Server needs the following ports:
- UDP port 9003
- TCP ports 9100-9200
EDIT: Sorry Nick, did not you already replied when I was posting this 
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