Lex, I read your post and the reply. Thank you very much for taking the time to write down your solution.
I agree with the IPv6 thing. It's better to disable the IPv6 in the server block. But I have done it system-wide by editing the /etc/gai.conf and uncomment the following line to set precedence to IPv4:
precedence ::ffff:0:0/96 100
I did so because my 'sudo apt-get update' used to get stuck at some point since it tries with IPv6. When the precedence is set to IPv4, its smooth. I guess you experienced something similar, though it was in the server block.
Regarding the 'default' file in the /etc/nginx/sites-enabled/ directory, after hosting multiple wordpress or non wordpress sites, the usual thing is to get rid of it. I have my 'default' file removed. So i didn't get a chance to experience that situation of IPv6 taking precedence and loading the 'default' page.
After 2 days of hair-pulling, you learned something useful.. so did I..