Where should /.well-known/acme-challenge/ point?

Help
4

I have created file in path /var/www/html/.well-known/acme-challenge/1234 and added

   location /.well-known/acme-challenge/ {
        root /var/www/html;
    }

to my Nginx. I can download the file 1234, however, running certbot renew gives

Attempting to renew cert (subdomain.myserver.com) from /etc/letsencrypt/renewal/subdomain.myserver.com.conf produced an unexpected error: Failed authorization procedure. subdomain.myserver.com (http-01): urn:ietf:params:acme:error:unauthorized :: The client lacks sufficient authorization :: Invalid response from https://subdomain.myserver.com/.well-known/acme-challenge/somerandomkeys [2606:4700:3032::681f:43b1]: "<html>\n<head><title>404 Not Found</title></head>\n<body bgcolor=\"white\">\n<center><h1>404 Not Found</h1></center>\n<hr><center>ngin". Skipping.
All renewal attempts failed. The following certs could not be renewed:
  /etc/letsencrypt/live/subdomain.myserver.com/fullchain.pem (failure)

What am I missing?

Thanks