Apache Guacamole + Nginx Proxy Manager = SyntaxError
Use no 'Custom Location'.
Put this in Advanced:
location / {
proxy_pass http://192.168.123.123:8080/guacamole/;
proxy_buffering off;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $http_connection;
proxy_cookie_path /guacamole/ /;
access_log off;
}