I don't think it's a problem with reloading the configuration file, because I have been reloading it every time after I update and save it.

What is happening is that when I run 'sudo nginx', it doesn't start and outputs this error:

nginx: [emerg] bind() to some_ip:some_port failed (49: Can't assign requested address)

I can access some_ip:some_port just fine from a browser and ssh-ing into it is not a problem.