Filebeat to match IIS logs timestamp

Christian, we are using ELK + Filebeat to ingest logs from IIS server. We had an issue where the service was not running and some old IIS logs were not imported from 2 weeks ago. I've turned filebeat service and the logs got ingested but the timestamp was used as current time of import. I would like logstash to read timestamp on the actual logs. I found these articles describing similar issue I tried to follow the steps described however was not successful.