All audio drops in one direction when multiple calls occur without restarting the client

[chanderlud]

• first call is fine
• second call drops all audio for 30 seconds or so
• one person can hear the other consistently, other gets full loss
• download bandwidth seems to indicate that packet loss is not the root cause (upload = download)

[chanderlud]

Proposed root cause is stale audio datagrams from the previous call arriving during the new call. This causes the new call to expect a high sequence number for the next valid audio frame, dropping the real audio from the new call.