Logging

[p1r473]

Recommend you enable logging
sudo echo "
log_format dns '$remote_addr:$remote_port - [$time_local] $protocol $status $upstream_addr $ssl_protocol $ssl_cipher - Server: $server_addr:$server_port - Connection: $connection';;
access_log /var/log/nginx/access.log dns;
error_log /var/log/nginx/error.log;
" >/etc/nginx/streams/dns-over-tls

Thanks for this page and your guide. Also, may help someone in testing their proxy:
kdig -d @YOUR-IP +tls-ca +tls-host=YOUR-DOMAIN DOMAIN

You also might want to look at other directives too:
proxy_responses 1;
proxy_timeout 1s;
server 127.0.0.1:53 fail_timeout=10s;