Nextcloud cannot be accessed publicly after assigning an ssl certificate using nginxproxymanager

Hi there,
I’m facing an issue accessing my nextcloud instance (running on docker) after I changed to a duckdns domain.
When I add an ssl certificate to the domain (via nginxproxymanager), I get this error when accessing the instance “Error code: SSL_ERROR_RX_RECORD_TOO_LONG”.
Could someone tell me what’s wrong?
I doubt that this is because something I’ve not configured on nextcloud.

domain :

Thanks and Sorry in advance, If you expect me to show you any logs please do let me know.