AWSのEC2のマーケットプレイスでRoundcube by bitnamiというツールを入手しました。
WEBメールツールで非常に便利なのですが、接続不良などのトラブルを起こします。
こういったことの対処についてサポートしてくれそうなところがなくて困っているのですが
（AWSではマーケットプレイスのものはサポート外扱い）ようやく見つけました。

サーバにまずはSSHでログイン

ssh -i *** bitnami@XX.XX.XX.XX

診断ツールを起動します。

$ sudo /opt/bitnami/bndiagnostic-tool
----------------------------------------------------------------------------
Welcome to the Bitnami Diagnostic tool.

----------------------------------------------------------------------------
Please read the following information carefully.

Press [Enter] to continue:
This tool collects system information and files from a Bitnami stack into a
diagnostic bundle file to be uploaded and reviewed by the Bitnami Team, for the
sole purpose of providing you support for any issue you may find.

The uploaded information will be automatically removed from our systems after 1
month. In case you have any doubt regarding our privacy policy please check:

https://www.vmware.com/help/privacy.html
Press [Enter] to continue:

Do you accept? [y/n]: y

||
The bndiagnostic tool has finished searching for errors and has found some
issues that might be related to yours. The output will be shown on the next
page:

Press [Enter] to continue:


===== Begin of bndiagnostic tool output =====


    ? Apache: Found possible issues
    ✓ Mariadb: No issues found
    ✓ Connectivity: No issues found
    ✓ Resources: No issues found
    ✓ Php: No issues found



[Apache]

Found recent error or warning messages in the Apache error log.
### 多分問題の箇所 ###
[Sat Sep 18 03:25:12.825188 2021] [authz_core:error] [pid 732:tid
eee] [client **ip_address**:54400] AH01630: client denied by server
configuration: /opt/bitnami/roundcube/config/aws.yml
 [Sat Sep 18 05:45:28.766500 2021] [authz_core:error] [pid 1532:tid
aaa] [client **ip_address**:58734] AH01630: client denied by server
configuration: /opt/bitnami/roundcube/config/getuser
 [Sat Sep 18 07:12:13.147052 2021] [authz_core:error] [pid 1533:tid
Press [Enter] to continue:
aaa] [client **ip_address**:42956] AH01630: client denied by server
configuration: /opt/bitnami/roundcube/config/getuser
###  ここまで ###

Please check the following guide to troubleshoot server issues:

https://docs.bitnami.com/general/apps/wordpress/troubleshooting/debug-erro
rs-apache/


===== End of bndiagnostic tool output =====


Press [Enter] to continue:
The diagnostic bundle was uploaded successfully to the Bitnami servers. Please copy the following code:

XXXXX-XXXX-XXXX-XXXX-XXXXX # これをコピーしておく

And paste it in your Bitnami Support ticket.

bitnami のコミュニティに問い合わせる

投稿の際に診断ツールのコードを聞かれるので貼り付けること。

もちろん内容は英語で書かないといけないのですがそこはエンジニア必須スキルなので頑張りましょう。

以上です。