HTTP Strict Transport Security (HSTS) tells browsers to use HTTPS for a website. A working HTTPS configuration is required.
This article concerns only the older Smart, Starter, Basic, Advanced, Premium and Platinum hosting plans in Austria. It does not apply to coffee hosting plans such as Mokka, Ristretto or Doppio.
The original setup instructions used a DNS change from 91.227.204.35 to 91.227.204.45.
These are legacy addresses. Before changing DNS, ask EDIS support whether this setup still applies to your specific hosting account and how to enable HSTS for it.