Thank you for your post and for your patience as we worked through the queue to reach your inquiry.
Most recent diagnostics show a successful login on a Windows RoonServer install with your account in the last few days.
Are you still encountering any issues with single sign-on?
We’re here to support if so. In the meantime, as a workaround, I suggest you try entering the web administration page for your router and changing the DNS servers to Cloudflare DNS, Quad9 or Google DNS.