I installed Roundcube on a Debian server running Dovecot, Postfix, mySQL for mail, and postfixadmin.
Then I installed Roundcube.
I have another server with the same configuration.
I can send and receive using IMAP/SMTP with Thunderbird. But when I connect using the Roundcube client I get the error:
Connection to storage server failed.
What process should I use to diagnose this?