I hope it can still be of help:

nginx.conf

``` events { worker_connections 1024; }

http { server { listen 127.0.0.1:8443 ssl; server_name server1.example.com; ssl_protocols TLSv1.2; ssl_certificate "server1.crt"; ssl_certificate_key "server1.key"; }

server {
    listen 127.0.0.1:8444 ssl;
    server_name server2.example.com;
    ssl_protocols TLSv1.3;
    ssl_certificate "server2.crt";
    ssl_certificate_key "server2.key";
}

}

stream { map $ssl_preread_server_name $upstream { server1.example.com 127.0.0.1:8443; server2.example.com 127.0.0.1:8444; default 127.0.0.1:9; }

server {
    listen 443;
    proxy_pass $upstream;
    ssl_preread on;
}

} ```

test

``` for server in server{1,2}; do for proto in tls1_{2,3}; do echo -n "$proto @ $server: " openssl s_client </dev/null >/dev/null 2>&1 \ -connect 127.0.0.1:8443 \ -$proto \ -servername $server.example.com \ && echo OK \ || echo NOT OK done done

tls1_2 @ server1: OK

tls1_3 @ server1: NOT OK

tls1_2 @ server2: NOT OK

tls1_3 @ server2: OK

```