i have found the issue. It is 100% Bungie's fault. As I thought, the issue lies on the software delivery servers for Austria and Croatia. What I did to solve was use a UK VPN on my router. This then allowed the PS4 to connect to a UK server. The software downloaded with no problems. I was lucky that I had a DD-WRT router and a UK VPN service. In other words, you need to trick your PS4 that you are in the UK, and it will work.