Can you elaborate on your Media Cache configuration? Is this local or remote from your Wowza server? As you've shown it looks like there is some connectivity issue between one and the other. Can you carry out some simple tests to see if there are any network issues while running this configuration. A simple ping from the Wowza server to the HTTP store (if this is remote from the Wowza server) may indicate issues with connectivity for example.
The timeouts and resets you are seeing is due to the web server not responding to the requests quickly enough. It could possibly be due to the web server getting overloaded. You could try increasing the httpReadTimeout & httpConnectionTimeout values but if the remote server is overloaded, then it would just cause a longer delay before resetting.
MediaCache always makes byte range requests but it may still cause playback errors if the data cannot be retrieved.