@baris
Thank you so much for confirming this. Since my config was working before, I changed my focus only to network and found the issue.
In my nginx config I had:
listen 80
listen 443 default ssl
Miraculously this had worked for last four years without issue. My server has 4 nic cards and nginx was listening to the wrong interface.
Modified nginx config to bound it to the right ip:port to solve the issue.
Happy to be back on-line and thanks for your support.
