Hello @gar77,
Thank you for the additional information.
Some users have reported temporary success on the Astell & Kern SR35 by sideloading a newer browser (such as Chrome) to replace the outdated system WebView used during ARC login. You’re welcome to try this workaround — in some cases it allows the CAPTCHA and login process to complete.
However, this is not a guaranteed or supported solution. If the workaround does not resolve the issue, the next step is to contact Astell & Kern support directly and request that they update the WebView / browser components in their firmware. ARC depends on modern WebView capabilities for authentication, and only the device manufacturer can provide those updates.
Please let us know how it goes.