Root Server with Ubuntu 16.04.
Nginx Version: 1.10.3

I have an Nginx server that serves 1 Application: An open source Cloud Server from Seafile that listens on cloud.mydomain.com

I now tried to add another Application to my server: A Mattermost server that should listen on chat.mydomain.com

When I am adding the Nginx config for Mattermost, then it only is available when I deactivate the Seafile nginx config.

So the server only serves one application at a time and that's always the Seafile Server.
Then no nginx error.logs or access.logs get any data from the Mattermost login attempts.

I am pasting the configs below and am hoping that someone could give me a tip what I have a done wrong or what I need to change.
I don't understand why Nginx does not listen for chat.mydomain.com

Any help would be very much appreciated!

SEAFILE NGINX CONFIG:

server {

listen 80 http2;
listen [::]:80 http2;
server_name cloud.mydomain.com;

rewrite ^ https://$http_host$request_uri? permanent; # force redirect http to https

# Enables or disables emitting nginx version on error pages and in the "Server" response header field.
server_tokens off;

}

server {
listen 443 ssl http2; # managed by Certbot
listen [::]:443 http2;
ssl on;

server_name cloud.mydomain.com;

ssl_session_cache shared:SSL:5m;
server_tokens off;

ssl_certificate /etc/letsencrypt/live/cloud.mydomain.com/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/cloud.mydomain.com/privkey.pem; # managed by Certbot

include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot

ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

proxy_set_header X-Forwarded-For $remote_addr;

add_header Strict-Transport-Security "max-age=31536000; includeSubDomains";

location / {
proxy_pass http://127.0.0.1:8000;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Host $server_name;
proxy_set_header X-Forwarded-Proto https;

proxy_read_timeout 1200s;

# used for view/edit office file via Office Online Server
client_max_body_size 0;

access_log /var/log/nginx/seahub.access.log;
error_log /var/log/nginx/seahub.error.log;
}

location /seafhttp {
rewrite ^/seafhttp(.*)$ $1 break;
proxy_pass http://127.0.0.1:8082;
client_max_body_size 0;

proxy_connect_timeout 36000s;
proxy_read_timeout 36000s;
proxy_send_timeout 36000s;
send_timeout 36000s;

proxy_request_buffering off;
}

location /media {
root /home/user/seafile.cloud/seafile-server-latest/seahub;
}

location /webdav {
fastcgi_pass 127.0.0.1:8080;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO $fastcgi_script_name;

fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name;
fastcgi_param HTTPS on;
fastcgi_param HTTP_SCHEME https;

client_max_body_size 0;
proxy_connect_timeout 36000s;
proxy_read_timeout 36000s;
proxy_send_timeout 36000s;
send_timeout 36000s;

# This option is only available for Nginx >= 1.8.0. See more details below.
proxy_request_buffering off;

access_log /var/log/nginx/seafdav.access.log;
error_log /var/log/nginx/seafdav.error.log;
}
}




MATTERMOST NGINX CONFIG:

upstream backend {
server 127.0.0.1:8065;
}

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=mattermost_cache:10m max_size=3g inactive=120m use_temp_path=off;

server {
listen 80;
listen [::]:80;
server_name chat.mydomain.com;

location ~/api/v[0-9]+/(users/)?websocket$ {
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
client_max_body_size 50M;
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Frame-Options SAMEORIGIN;
proxy_buffers 256 16k;
proxy_buffer_size 16k;
proxy_read_timeout 600s;
proxy_pass http://backend;
}

location / {
client_max_body_size 50M;
proxy_set_header Connection "";
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Frame-Options SAMEORIGIN;
proxy_buffers 256 16k;
proxy_buffer_size 16k;
proxy_read_timeout 600s;
proxy_cache mattermost_cache;
proxy_cache_revalidate on;
proxy_cache_min_uses 2;
proxy_cache_use_stale timeout;
proxy_cache_lock on;
proxy_pass http://backend;
}
}