Lets Encrypt determines that it cannot connect (Dynamic IP)

Currently, Debian is considering transferring to Let's Encrypt due to the price increase of RapidSSL WildCard (10,000 yen → 20,000 yen).
The CentOS on the VPS worked fine, and I was able to make it work without any problems, but authentication failed on the home server (dynamic IP).It didn't work automatically, so I'm trying to deploy it with --manual.

./letsencrypt-autocertonly --manual-d#MY-DOMAIN# --server HTTPS://acme-v01.api.letsencrypt.org/directory

First, we started creating a key file with the above command.

http://#MY-DOMAIN#/.well-known/acme-challenge/#LONG-RANDOM-FILENAME#

I wrote "#LONG-RANDOM-STRING#" in the corresponding "#LONG-RANDOM-FILENAME#" to be accessed by the .Tried the command print "%S" #LONG-RANDOM-STRING#>#LONG-RANDOM-FILENAME# and "echo" #LONG-RANDOM-STRING#" > #LONG-RANDOM-FILENAME# as shown.
I confirmed that I can see it if I access the specified URL from my browser and returned it.Then I got the following error:

IMPORTANT NOTES:
 - The following errors were reported by the server:

   Domain: #MY-DOMAIN#
   Type: connection
   Detail—Could not connect to
   http://#MY-DOMAIN#/.well-known/acme-challenge/#LONG-RANDOM-FILENAME#

   To fix these errors, please make sure that your domain name was
   entered correctly and the DNS Record(s) for that domain
   contain(s) the right IP address.Additionally, please check that
   your computer has a publicly routable IP address and that no
   firewalls are presenting the server from communicating with the
   client.If you're using the webroot plugin, you should verify
   That you are serving files from the webroot path you provided.

I disabled the firewall on the router and server because of the inaccessible error, but when I checked DNS on Dig, I found that the IP that has not changed since more than a month ago was in A record.

;QUESTION SECTION:
   ;#MY-DOMAIN#.INA

   ;; ANSWER SECTION:
   #MY-DOMAIN#.120 IN A#MY-SERVER-IPADDR#

However, when I checked the access log and error log of the server, it seems that there is no access from the authentication server, and it seems that the correct IP address is not delivered to the authentication server.
What should I do in this case?