The Barclays bit goes fineif I use mobile banking; the error occurs on Barclays’ page if I try to use online banking. The Open Banking page on QuickFile is where I see the notice about lack of connectivity.
I’ve now revoked access to try to force a new connection with the same results - I get the same 6013 error when using online banking, and while the Barclays steps seem to work with mobile banking, when I’m redirected to your site again, I get the error about the Barclays authorisation server returning an error.