Problem with newly added subdomain is automatically redirect to SSL

Hi all,

I’ve already had a droplet which previously has been setup with:

• Nginx server
• A domain (example.com)
• Re-route www.example.com to example.com as always.
• Installed and config Let’s Encrypt for both example.com and www.example.com
• All HTTP will be redirected to HTTPS.

So at current state, all will be redirected to https://example.com and it is working fine.

Now, I want to add a subdomain into this droplet. I visit Networking section, add a new A record

sub.example.com. 1800 IN A 123.45.67.89

The ping works fine, it can send the packets.

When I type the address sub.example.com to web browser, I mean plain http://sub.example.com, it just automagically redirects to https://sub.example.com while I haven’t set up anything for SSL.

I also tried to add a virtual host entry for sub.example.com to nginx server, it just keeps redirects to the same route https://sub.example.com.

I added access_log, error_log to nginx server config. No entry added if I visit the sub-domain.

Anyone have idea on this case? I search over Internet but haven’t found any case similar to mine.