Voip unstable on WIFI

Hi,
Has anyone had problems with VOIP in wifi connection ? My client tests voip on two laptops connected to wifi and he gets a stutter on the computer holding the server and sometimes on both when the laptops are in different rooms . I got some logs from him too but there isn’t much information in them on this problem :

I had stuttering issue with my network extensive physics replicating project. And fixed with default network transfer limit of UE4. So, try to add these to your DefaultEngine.ini.

[/Script/Engine.Player]
ConfiguredInternetSpeed=1000000000 
ConfiguredLanSpeed=1000000000 

[/Script/OnlineSubsystemUtils.IpNetDriver]
MaxClientRate=1000000000 
MaxInternetClientRate=1000000000 

Also how you get working VoIP with OnlineSubsystemNull ? I never able to get it working it though I haven’t spend much time on it but it is in my backlog. Can you please explain that to me ?

Yeah! That fixed stutter in VOIP on our PC game, Unfortunate Spacemen.

Our connections were not on WiFi.

Many thanks.