The version of mono listed in Sonarr is 3.10.0 (tarball Mon Jan 26 02:53:37 UTC 2015).
This is all within my local network, there aren’t any hardware or software firewalls that I’m aware of. Additionally, the computer I’m accessing Sonarr from is able to use a version installed on a separate Ubuntu VM without issue.
I’m not very familiar with the developer console, but I do see this:
starting signalR
app.js?v=2.0.0.2722:31106 SignalR: [connecting]
app.js?v=2.0.0.2722:67676 starting signalR
app.js?v=2.0.0.2722:8706 GET http://192.168.16.162:15001/signalr/negotiate?_=1424218930937 500 (Internal Server Error)
app.js?v=2.0.0.2722:31106 SignalR: [disconnected]
Looks like signalr is throwing a 500 error. I’m not very good with Linux, though, so I’m unsure of how I might be able to resolve it.