Unattended Support not Connecting

Hi,
I'm having an issue this morning where I am unable to access any of my 50+ PC's on Zoho Assist Unattended. They are showing as Online but when I click on them they start to connect and get stuck on "Starting Support Session". Speaking to my clients, it seems they get a pop up asking them to enter Proxy details. They aren't behind a proxy.

Please help, I need to help customers!

Thanks,