darktower02.asuscomm.com is currently affected by Let's Encrypt-based rate limits (https://letsencrypt.org/docs/rate-limits/). You may review certificates that have already been issued by visiting https://crt.sh/?q=%asuscomm.com . Please note that it is not possible to ask for a rate limit to be manually cleared.
The 'Certificates per Registered Domain' limit (50 certificates per week that share the same Registered Domain: asuscomm.com) has been exceeded. There is no way to work around this rate limit. The next non-renewal certificate for this Registered Domain should be issuable after 2021-09-24 21:42:53 +0000 UTC (2m0s from now).
A private, inaccessible, IANA/IETF-reserved IP address was found for darktower02.asuscomm.com. Let's Encrypt will always fail HTTP validation for any domain that is pointing to an address that is not routable on the internet. You should either remove this address and replace it with a public one or use the DNS validation method instead.
100.93.17.54