Sorry to say you must google on your own, you seem to be on some shitty hardware thats beyond the scope of my knowledge.
Try this video its as far as I came, look what is done and repeat with your numbers.
Perhaps change “WAN Interface” if possible when portforwarding. I cant help you anymore as we have done what I know are the necessary steps to get it working, and your port 443 is still blocked from outside. I’d say it’s a part of the issue. Once you resolve it perhaps then Let’s Encrypt will work.