Exim is sending localhost IP address in HELO

Error in email received from my hestia EXIM server by remote mailserver:
Your IP address does not resolve to localhost (unknown []) by server.contrid.net (Postfix) with ESMTP id C49864926 for ; Wed, 5 Jul 2023 11:03:43 +0000 (UTC)

have tried editing the exim config files for SMTP_active_hostname but not succeeded in getting the actual server IP passed in HELO.
have checked the ‘hostname - f’ on server and its reporting my domain correctly.

Any help much appreciated