Dean
This happens to me also on my mobile device however when I turned my WiFi off and used my mobile data it worked
Hi Dean,
This suggests that in your case the issues is the your ISP or Wi-Fi setup. Specific ports need to be accessible to be able to use the transfer system. I have the same issue here in work as my work proxy blocks those ports. When your on mobile data you are accessing via a different provider who is not blocking these ports.