srimuang.ddns.net has an A (IPv4) record (182.232.224.166) but a request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address.
A timeout was experienced while communicating with srimuang.ddns.net/182.232.224.166: Get "http://srimuang.ddns.net/.well-known/acme-challenge/letsdebug-test": context deadline exceeded
Trace:
@0ms: Making a request to http://srimuang.ddns.net/.well-known/acme-challenge/letsdebug-test (using initial IP 182.232.224.166)
@0ms: Dialing 182.232.224.166
@10000ms: Experienced error: context deadline exceeded
A test authorization for srimuang.ddns.net to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
182.232.224.166: Fetching http://srimuang.ddns.net/.well-known/acme-challenge/OjjhUWQ2juFkj26Xv0ljY2RnJ2eUPJni6HmSrKi5EFQ: Timeout during connect (likely firewall problem)