Audio cuts regularly in and out and video freezes (US vs AUSTRALIAN ZOOM)

My own and my client's audio cuts regularly in and out and video freezes for 3 seconds at the same time. During every call of 90 min at least 10+ times. A client told me that he has fixed this by switching from the US server / satellite / domain to the Australien server / satellite / domain.  I have tried to find out how to do this. Can anyone send me in the right direction, please? Thanks in advance.