The certificate worked for about three months. It stopped working for no (objective) reason, I didnāt change anything. Do you really think thereās a problem in IPv4/IPv6? I can provide domain name in PM it really works and works right, but certbot canāt get files.
Using the domain name that you sent in your PM, I checked with IPv4 and IPv6 and found that while they both answer requests, they have different content. So thatās probably the reason; your IPv6 webroot or equivalent doesnāt match your IPv4 webroot.
Wow! I really had correct ipv4 and incorrect ipv6 DNS records. Thank you so much, guys! It was not obvious (for me) and certbot used to work well for about 3 months. I am very grateful to you. How can I thank you? I eat this banana for your health!