Why does the Rincon audio seem to slow down, speed up or change pitch?

This type of audio anomaly indicates there are lost audio packets. You can check to see if the audio streams are reaching the Decoder Rincon error free by checking the following Rincon WEB GUI pages.

Statistics -> IP Streams  (check for Sequence Errors, it should be zero)
Statistics -> E1T1 Streams (check for Sequence Errors, it should be zero)

In addition to the Stream Statistics, the Event Log might also be helpful. The Event Log records when audio is lost due to Ethernet packet loss or delay or T1 line errors. Examine the Event Log for "DP" entries like this:   

04/26/19 11:01:41 ID 1 DP 11902*

The Rincon normally logs a DP entry every few minutes. You only need to watch for an increase in the count. If there is an "*" symbol on the end of the entire this indicates there was an increase in the dropped packet count since the previous log entire.