Ex7700 extender wifi calling drops

Hi all,
I have an issue where if I’m on a Wi-Fi call on my smart phone, the call drops. General the caller can still hear me but I can’t hear them.

The fault appears when I move between the extender, to my main provider’s Wi-Fi hub. I’m sure if it it happens that way round or if when I go from my main hub to the extender.

I’m with virgin media and have fibre optic and the speed is not a concern.

Has anyone experienced this before or know how to fix the bug?
Cheers