A Server restarted and Website giving 502 Bad Gateway - ruby-on-rails

Question

So i was asked to check this server out that after a restart is giving an 502 bad gateway message.
It's an nginx 1.10.3 in an ubuntu
I was looking around and what I can see is this:
in /var/log/nginx/error.log:
2020/03/18 02:29:45 [error] 3166#3166: *474 connect() to unix:/home/ubuntu/xxx/shared/tmp/sockets/puma.sock failed (111: Connection refused) while connecting to upstream, client: 190.162.83.37, server: 127.0.0.1, request: "GET / HTTP/1.1", upstream: "http://unix:/home/ubuntu/xxx/shared/tmp/sockets/puma.sock:/500.html", host: "domain.website.com"
I see this error multiple times. All I was told is that the website was working fine until it was rebooted. Apparently the server had been working non-stop for months.
The nginx.conf config is:
user www-data;
worker_processes auto;
pid /run/nginx.pid;
events {
worker_connections 1024;
# multi_accept on;
}
http {
uwsgi_connect_timeout 75s;
proxy_connect_timeout 600;
proxy_send_timeout 600s;
proxy_read_timeout 600s;
fastcgi_send_timeout 600s;
fastcgi_read_timeout 600s;
##
# Basic Settings
##
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;
# server_names_hash_bucket_size 64;
# server_name_in_redirect off;
include /etc/nginx/mime.types;
default_type application/octet-stream;
##
# SSL Settings
##
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
ssl_prefer_server_ciphers on;
##
# Logging Settings
##
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;
##
# Gzip Settings
##
gzip on;
gzip_disable "msie6";
# gzip_vary on;
# gzip_proxied any;
# gzip_comp_level 6;
# gzip_buffers 16 8k;
# gzip_http_version 1.1;
# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
##
# Virtual Host Configs
##
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}
#mail {
# # See sample authentication script at:
# # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
#
# # auth_http localhost/auth.php;
# # pop3_capabilities "TOP" "USER";
# # imap_capabilities "IMAP4rev1" "UIDPLUS";
#
# server {
# listen localhost:110;
# protocol pop3;
# proxy on;
# }
#
# server {
# listen localhost:143;
# protocol imap;
# proxy on;
# }
#}
And the /etc/nginx/sites-enabled/default file:
upstream app {
# Path to Puma SOCK file, as defined previously
server unix:/home/ubuntu/xxx/shared/tmp/sockets/puma.sock fail_timeout=0;
}
server {
listen 80;
server_name 127.0.0.1 172.31.0.59;
root /home/ubuntu/xxx/current/public;
try_files $uri/index.html $uri #app;
location / {
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Connection '';
proxy_pass http://app;
}
location ~ ^/(assets|fonts|system)/|favicon.ico|robots.txt|A8774B2003352D7DCA9406C3FADC610B.txt|sitemap.xml|video.mp4 {
gzip_static on;
expires max;
add_header Cache-Control public;
}
error_page 500 502 503 504 /500.html;
client_max_body_size 4G;
keepalive_timeout 10;
}
server {
listen 443 ssl;
server_name 127.0.0.1 172.31.0.59;
ssl_certificate /home/ubuntu/xxx/shared/cert/demain.website.com.crt;
ssl_certificate_key /home/ubuntu/xxx/shared/cert/demain.website.com.key;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers HIGH:!aNULL:!MD5;
#maintenance
error_page 503 /maintenance.html;
location /maintenance.html {
# allow access to this specific page
}
#location / {
# return 503;
#}
# Tell Nginx and Passenger where your app's 'public' directory is
root /home/ubuntu/xxx/current/public;
try_files $uri/index.html $uri #app;
location / {
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Connection '';
proxy_pass http://app;
}
location ~ ^/(assets|fonts|system)/|favicon.ico|robots.txt|A8774B2003352D7DCA9406C3FADC610B.txt|sitemap.xml|video.mp4 {
gzip_static on;
expires max;
add_header Cache-Control public;
}
error_page 500 502 503 504 /500.html;
client_max_body_size 4G;
keepalive_timeout 10;
# Turn on Passenger
#passenger_enabled on;
#passenger_ruby /usr/share/rvm/gems/ruby-2.4.2/wrappers/ruby;
#passenger_app_env stage;
}
I don't know what to do. Please Help.