VoIP drops out continuously

We installed VM last year and use our phone  plugged into the hub.

But EVERY single call it will drop out at 8 minutes 45 seconds.

EVERY.SINGLE.TIME.

Can someone explain why?? Tried calling customer “service “. That was fun…

Try resetting hub, try unplugging and plugging, stand on one leg…. Useless.

Is this a common fault?