Several times a day the browser will return a 'page not found' error, after a minute or so a refresh might show a 'TLS\SSL error' and after a couple of minutes more CAM will be back online. A proxy service restart clears it up straight away.
The best practice guide recommendations had not been implemented so its possible that the proxy was running out of available HTTP connections.
We raised the maxThreads value to the max 12200 and also added the disableKeepAlivePercentage="99" parameter and restarted the proxy service. We also recommended adding additional STS and proxy servers to reduce the load on any single server.