Hi  @rubenzsolt 

The configuration on the Omada controller looks correct. The error is SSL related, you can enable SSL to have a try. If still the same, you may refer to the following:

The error you're seeing is related to SSL/TLS, which is a protocol for secure communication over a computer network. The error message suggests that there's an issue with the SSL certificate on the server you're trying to connect to.

Here are a few things you could try to fix this issue:

1. Check the Certificate: Ensure that the certificate is correctly installed on the server. It should be a valid certificate issued by a trusted Certificate Authority (CA). If you're the server administrator, you might need to check the server configuration.

2. Update your System: Make sure your operating system and the software you're using to connect to the server (like a web browser or a client application) are up to date. Sometimes, older software versions have compatibility issues with newer SSL/TLS protocols.

3. Check the Date and Time: An incorrect system date/time can cause SSL errors. Make sure your computer's date and time are correct.

4. Disable SSLv3: The error message suggests that SSLv3 is being used, which is an outdated protocol with known security vulnerabilities. If possible, disable SSLv3 in your application or server configuration and use a more secure protocol like TLS 1.2 or TLS 1.3.

5. Contact the Server Administrator: If you're a client trying to connect to a server and you're seeing this error, you might need to contact the server administrator or the support team for the service you're trying to use. They might need to update or fix their SSL configuration.

  @Vincent-TP 

Hi, the mail server (Postfix) is on the local network without a trusted certificate because it is only for local delivery and I don't want to expose it to the internet.

Time is OK

The SSL3 it is disabled on mail server. 
smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3
smtp_tls_mandatory_protocols=!SSLv2,!SSLv3
smtpd_tls_protocols=!SSLv2,!SSLv3
smtp_tls_protocols=!SSLv2,!SSLv3

Hi  @rubenzsolt 

Where is the following from?

ERROR

connect from unknown[192.168.1.253]
SSL_accept error from unknown[192.168.1.253]: -1
warning: TLS library problem: error:0A000416:SSL routines::sslv3 alert certificate unknown:../ssl/record/rec_layer_s3.c:1590:SSL alert number 46:

The reason should be the untrusted certificates are not accepted by the device/server.