Some websites under science.ru.nl may be inaccessible
Several users have reported that they can no longer access websites such as http://example.science.ru.nl.
Browsers block these connections because the parent domain ru.nl now requires HTTPS, while some websites, often served directly from devices or sensors, do not support encrypted connections.
We are working on a general solution and will update this article once it becomes available.
Background: HTTP Strict Transport Security (HSTS)
Modern browsers enforce HTTP Strict Transport Security (HSTS) to prevent unencrypted HTTP access. Domains can opt in by being listed on hstspreload.org. Once listed, all subdomains must use HTTPS, and browsers will block HTTP entirely.
The domain ru.nl was added to the HSTS preload list in November 2025. This enforces HTTPS for all subdomains, including *.science.ru.nl. While this improves security, it causes issues for simple or embedded web servers that cannot support HTTPS.
Possible workarounds:
- Accessing the site via its IP address
- Using an alternative domain via a local hosts file
- Disabling HSTS in a specific browser (not recommended)