Thanks Chris for the follow up comment.

The issue was initially raised when no contacts of the contestants were able to vote and the reported this to the contestants who reported to us. They are all unconnected people from a number of countries who are trying to cast their vote for their favorite to win the prize as guests to the site and none have been able to do so.

When I did the confirmatory test I later mentioned, the phone device uses a different (mobile data) connection from the laptop device.

Hoping this help to put further context to it.