I have this in my DefaultEngine.ini for an online Steam voice project. I’m not sure if it helps but I heard voice needs greater than the default 10k per client.
[/Script/OnlineSubsystemUtils.IpNetDriver]
MaxClientRate=30000
MaxInternetClientRate=60000
[/Script/Engine.Player]
ConfiguredInternetSpeed=30000
ConfiguredLanSpeed=60000
Maybe worth a try. Good luck.