Erro de comprimento de chave inválido ao tentar conectar o phpmyadmin ao MySQL remoto por SSL

Question

Eu recebo essas mensagens de erro ao efetuar login na instância do phpmyadmin

Error during session start; please check your PHP and/or webserver log file and configure your PHP installation properly. Also ensure that cookies are enabled in your browser.

mysqli_query(): SSL operation failed with code 1. OpenSSL Error messages: error:0607A082:digital envelope routines:EVP_CIPHER_CTX_set_key_length:invalid key length error:0607A082:digital envelope routines:EVP_CIPHER_CTX_set_key_length:invalid key length

mysqli_query(): MySQL server has gone away

mysqli_query(): Error reading result set's header

Eu tenho a configuração mysql certificada "auto-assinado" nos hosts e a partir do maching rodando o phpMyAdmin eu consigo conectar ao MySql remoto através do cliente mysql

expro_app@ubuntu-app:/etc/mysql$ mysql --ssl-ca=ca-cert.pem --ssl-cert=client-cert.pem --ssl-key=client-key.pem -h XX.XXX.X.103 -P 7306 -u admin_secure -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 45
Server version: 5.5.49-0ubuntu0.14.04.1 (Ubuntu)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> status;
--------------
mysql  Ver 14.14 Distrib 5.5.49, for debian-linux-gnu (x86_64) using readline 6.3

Connection id:      45
Current database:   
Current user:       admin_secure@ubuntu-app
SSL:            Cipher in use is DHE-RSA-AES256-SHA
Current pager:      stdout
Using outfile:      ''
Using delimiter:    ;
Server version:     5.5.49-0ubuntu0.14.04.1 (Ubuntu)
Protocol version:   10
Connection:     XX.XXX.X.103 via TCP/IP
Server characterset:    latin1
Db     characterset:    latin1
Client characterset:    utf8
Conn.  characterset:    utf8
TCP port:       7306
Uptime:         2 days 8 hours 7 min 31 sec

Threads: 1  Questions: 126  Slow queries: 0  Opens: 48  Flush tables: 1  Open tables: 41  Queries per second avg: 0.000

Aqui estão as configurações do phpMyAdmin

/* Authentication type */
$cfg['Servers'][$i]['auth_type'] = 'cookie';
/* Server parameters */
$cfg['Servers'][$i]['host'] = 'XX.XXX.X.103';
$cfg['Servers'][$i]['port'] = 'XXXX';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['compress'] = false;
$cfg['Servers'][$i]['AllowNoPassword'] = false;
$cfg['Servers'][$i]['ssl']=true;
$cfg['Servers'][$i]['ssl_key'] = '/etc/mysql/client-key.pem';
$cfg['Servers'][$i]['ssl_cert'] = '/etc/mysql/client-cert.pem';
$cfg['Servers'][$i]['ssl_ca'] = '/etc/mysql/ca-cert.pem';
$cfg['Servers'][$i]['ssl_ciphers'] = 'DHE-RSA-AES256-SHA';
$cfg['Servers'][$i]['ssl_verify'] = false;

Estou definindo ssl_verify = false para evitar a verificação de ceritifcados auto-assinados, dado o pequeno hack em libraries/dbi/DBIMysqli.php

if ($cfg['Server']['ssl']) {
            mysqli_ssl_set(
                $link,
                $cfg['Server']['ssl_key'],
                $cfg['Server']['ssl_cert'],
                $cfg['Server']['ssl_ca'],
                $cfg['Server']['ssl_ca_path'],
                $cfg['Server']['ssl_ciphers']
            );
            /*
             * disables SSL certificate validation on mysqlnd for MySQL 5.6 or later
             * @link https://bugs.php.net/bug.php?id=68344
             * @link https://github.com/phpmyadmin/phpmyadmin/pull/11838
             */
            if (! $cfg['Server']['ssl_verify']) {
                mysqli_options(
                    $link,
                    MYSQLI_OPT_SSL_VERIFY_SERVER_CERT,
                    $cfg['Server']['ssl_verify']
                );
                $client_flags |= MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT;
            }
        }

Os logs de erro também não ajudam, nenhuma mensagem do OpenSSL. No servidor remoto, nada relacionado ao endereço IP da máquina phpMyAdmin na máquina do servidor MySql.

O que estou perdendo aqui?