We're aware of issues affecting some customers when processing 3DS verification via our payments partner Barclaycard, resulting in a "connection reset" browser error. We believe this issue is only affecting a portion of Visa cards at present.
This issue was identified as being in Arcot's network (supplier of 3D Secure software to some issuers) and has now been resolved.
We've received confirmation that this is a payment network technical issue and is affecting both VISA and MasterCard 3DS verifications. The cause has been identified and is being worked on. We apologise for the ongoing outage which is unfortunately out of our direct control.