Please try this if you want to add the port.
| makeresults
| eval dest="example.com", dest_port=8441
| lookup sslcert_lookup dest dest_port OUTPUT ssl_subject_common_name ssl_subject_alt_name ssl_end_time ssl_validity_window
| eval ssl_subject_alt_name = split(ssl_subject_alt_name,"|")
| eval days_left = round(ssl_validity_window/86400)
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