Hi. Apologies, I reached my message limit for 24h, which was annoying. I updated certificates by following this, which seemed to update them https://bobmckay.com/i-t-support-networking/security/hak5-keycroc-problems-connecting-to-cloud-c2-when-https-is-used/
I copied device.config to udisk using the windows directory. That didn't solve the issue, so I then used scp to copy it also onto the file system root.
Many thanks for your help. However, I think I'll just return the item, as I think it should work without having to go through hours of troubleshooting, especially having followed guidance closely. The most recent firmware seems to be 2020.