Resumo
Updated clients which support the DAVE (Audio & Video End-to-End Encryption) Protocol are now required to connect to non-stages voice calls across the Discord Platform. If you attempt to connect with an out of date client, the voice gateway will reject your connection with close code 4017. See https://support.discord.com/hc/en-us/articles/38025123604631-Minimum-Client-Version-Requirements-for-Voice-Chat for minimum client version requirements and https://support.discord.com/hc/en-us/articles/25968222946071-End-to-End-Encryption-for-Audio-and-Video for further details.