Website times out sporadically: ERR_TIMED_OUT and can't ssh into instance with nginx and EC2 setup

I am running a django app with nginx as webserver on an EC2 instance. The website gets a decent amount of API calls per minute depending on how many testpipelines I run. My problem is that the website times out sporadically. I can't reach it in the browswer and all my tests fail of course. Also I can't login to my instance anymore but have to wait until it is back up.... SHouldn't I at least be able ssh into it even though the website times out??

Now I am wondering: Is that rather an nginx configuration error or could it be that my EC2 does not have enough memory? I am deploying to an t2 micro instance on EC2 which has 1 vCPU and also only 1GB of memory. Let's say I get 20-30 API calls, all trying to download files between 10 and 50 MB. Do I need a bigger instance or should it be no problem to handle for the EC2?

Or could it be my nginx configuration? Right now I use this (I am not at all an nginx expert, please tell me if there are stupid configs set):

main config

user  nginx;
worker_processes auto;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections 1024;
    use epoll;
    multi_accept on;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    tcp_nopush      on;
    tcp_nodelay    on;
    send_timeout       90;
    keepalive_timeout  90;
    fastcgi_read_timeout 120;
    proxy_read_timeout 120;
    fastcgi_buffers 8 128k;
    fastcgi_buffer_size 128k;
    client_body_timeout 120;
    client_body_buffer_size 128K;
    client_header_buffer_size 1k;
    large_client_header_buffers 4 8k;
    client_header_timeout 120;
    client_max_body_size 5G;

    types_hash_max_size 2048;
    server_tokens off;

    gzip  on;
    gzip_static on;
    gzip_min_length 512;


    include /etc/nginx/conf.d/*.conf;
}

And server config

server {

    listen 443 ssl;
    server_name mywebsite.de;
    proxy_max_temp_file_size 0;
    proxy_buffering off;
    charset utf-8;
    ssl_stapling off;
    ssl_stapling_verify off;

    ssl_certificate            /etc/letsencrypt/live/mywebsite.de/fullchain.pem;
    ssl_certificate_key       /etc/letsencrypt/live/mywebsite.de/privkey.pem;


    set $my_host $http_host;
    if ($http_host = "mywebsite.de") {
          set $my_host "mywebsite.de";
    }


    location / {
        proxy_pass http://django:5000;
        proxy_set_header Host $my_host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_read_timeout 3600; 
  }

}

server {
        listen 80 ;
        server_name mywebsite.de;
        return 301 https://mywebsite.de$request_uri;
}
server {
        listen 80 ;
        server_name www.mywebsite.de;
        return 301 https://mywebsite.de$request_uri;
}
server {
        listen 443 ;
        server_name www.mywebsite.de;
        return 301 https://mywebsite.de$request_uri;
        ssl_stapling off;
        ssl_stapling_verify off;

        ssl_certificate           /etc/letsencrypt/live/mywebsite.de/fullchain.pem;
        ssl_certificate_key       /etc/letsencrypt/live/mywebsite.de/privkey.pem;
}

It could also be something else, but what else could crash my machine? Maybe Redis? I am not sure. I am looking for possible reasons this could happen and for possible solutions to have this as stable as possible.

Very grateful to the community for any help! Thanks in advance!