Создаем сайт:

```
sudo nano /etc/nginx/sites-available/kasm
```

Вставляем вот это чтобы нормально конфигурировало:

```
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name kasm.stitch505.su;
    
    access_log /var/log/nginx/kasm_access.log;
    error_log /var/log/nginx/kasm_error.log;
    
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;

    location / {
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        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-Proto $scheme;
        proxy_set_header X-Forwarded-Port 443;
        
        proxy_http_version 1.1;
        proxy_read_timeout 1800s;
        proxy_send_timeout 1800s;
        proxy_connect_timeout 1800s;
        proxy_buffering off;
        proxy_ssl_verify off;
        client_max_body_size 10G;
        
        proxy_pass https://127.0.0.1:5443;
    }
}
```

Сохраняем, выходим, активируем сайт и перезапускаем nginx:
```
sudo ln -s /etc/nginx/sites-available/YOURDOMAIN /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx
```