Problem with SMTP system setup

[kromsam]

I wanted to configure the SMTP server. But this didn't work. The problem is not with the credentials I used, because I used the same with Firefox.

When I fill in the credential is the Nextxloud GUI I get the following error:

Connection could not be established with host smtp.domain.tld [Operation timed out #110])

[kromsam]

sudo docker exec --user www-data nextcloud php occ config:system:set mail_smtptimeout --value="30"

did not work

also

sudo ufw allow 465

did not work