このエラーメッセージに関する原因と対処に関して説明します。
エラーメッセージ(英語)：
unable to establish ssl connection
対処
関連リンク
Unable to establish SSL connection upon wget on Ubuntu 14.04 LTS ...
https://stackoverflow.com/questions/28757232/unable-to-establish-ssl-connection-upon-wget-on-ubuntu-・・・
wget returns "Unable to establish SSL connection"
https://stackoverflow.com/questions/50292852/wget-returns-unable-to-establish-ssl-connection
Wget over SSL gives: Unable to establish SSL connection
https://stackoverflow.com/questions/36832118/wget-over-ssl-gives-unable-to-establish-ssl-connection
Problems setting self-signed ssl certificate in couchdb at ...
https://stackoverflow.com/questions/19081676/problems-setting-self-signed-ssl-certificate-in-couchdb・・・
Unable to establish SSL connection, how do I fix my SSL cert ...
https://stackoverflow.com/questions/15166950/unable-to-establish-ssl-connection-how-do-i-fix-my-ssl-・・・
wgetで「Unable to establish SSL connection」エラー | ぽちゃ猫.com
https://www.pochaneko.com/wget-sslerror/
curl - Unable to establish SSL connection with wget - Server Fault
https://serverfault.com/questions/807481/unable-to-establish-ssl-connection-with-wget
Unable to access a server with a self-signed SSL certificate from ...
https://serverfault.com/questions/895900/unable-to-access-a-server-with-a-self-signed-ssl-certificat・・・
ssl - curl succeeds on an https request, wget does not
https://serverfault.com/questions/560053/curl-succeeds-on-an-https-request-wget-does-not
SSL connection errors from Apache
https://serverfault.com/questions/179628/ssl-connection-errors-from-apache