Multiple server blocks using same port

Hello. I have a problem with Nginx. I have three websites running, and all using the same 443 port for SSL. When I try to restart Nginx, I get an error like the following:

root@vps:~# nginx
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:443 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:443 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:443 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:443 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
nginx: [emerg] bind() to [::]:443 failed (98: Address already in use)
nginx: [emerg] still could not bind()

Here is my nginx "default" file: https://hastebin.com/ejuwapafup.nginx

I had gotten it to work before on Ubuntu 16.04.3, but when I switched to Debian 9, it caused this issue.

If you can help, please do!