Also, your IPv6 address in your DNS AAAA record is not a working IP address
Let's Encrypt prefers IPv6 when you have an AAAA record but will try IPv4 for certain failures. But, this is not good to rely on and only works for narrow cases.
You should fix your IPv6 address or remove it if you cannot support IPv6. This problem affects all ports.
curl -i4 http://rpiweather.net
HTTP/1.1 301 Moved Permanently
Server: nginx/1.14.2
curl -i6 http://rpiweather.net
curl: (7) Failed to connect to rpiweather.net port 80 after 3017 ms:
No route to host
Also see