On my Roon apply, my streamer Wattson Audio Emerson no longer appears at the bottom right of my screen. I only have the System Output option with the speaker icon, but no longer Wattson.
Describe your network setup
I use a Mac Book Pro, a Wattson Audio streamer model Emerson) and a DAC Jadis JS2 MKII
We have just retrieve a piece of diagnostic data reported from your Roon app to us and can see that your machine had following record
Warn: [raat_ll/client] [Wattson Audio Emerson DIGITAL @ 192.168.1.12:49638] failed to connect(0) No route to host
No route to host - it means that your mac could discover the Streamer via mDNS or multicast but cannot establish TCP connection.
There might be plenty of reasons for that.
Make sure that your mac is not Connected to multiple network interfaces (i. e. uses only wi fi or ethernet, but not together).
Disable firewall temporarily if present
Your mac has tight network security settings, so please go to Settings>Security & Privacy>Local Network and retoggle the options for Roon and Roon Server
disable QoS temporarily on your router if enabled
power off your local network infrastructure for few minutes, then reboot it, reboot mac and your audio streamer → and try to connect again to it.