Whatsapp call failed when call on hold or make new call

Hello this has only started to happen recently and cannot find a fix for it.

whenever I am on a whats app call and get a normal call, I press the hold and accept, my whats app call says hold then I watch it say call failed a few seconds later. same if I try to place a call while on the call.

I have tried reinstalling whats app, updated phone, reset network settings,

this has never been a problem before and could always hold my whatsapp call before.

I really am stuck on what I could try without having to reset my whole phone.

I have 4g/wifi most of the time with no signal issues, all my call waiting settings are turned on and I have tried turning them all on and off. I have done allot of searching and tried allot of steps to resolve it. this might not be a big problem for most people but I am on call almost 24/7 and it's a massive inconvience not being able to answer while on call.

thanks