I have two datasets that update two separate reports respectively, and I have set the datasets to automatically refresh every morning at 10:30. I am refreshing from the PowerBI service from the cloud. There is a gateway included. The scheduled refresh for one report took 17 minutes to update whilst the refresh on the other took over an hour. When I manually refresh, it doesn't take longer than two minutes. Is there anything I can do to shorten the length of the scheduled refresh?
Your question is very broad, it should possibly be closed, but I'll give you a few places to look.
Are you manually refreshing from the PowerBI service? Remember that PowerBI service refreshed from the cloud and PowerBI desktop refreshed from your machine. So the location of your data sources matters here. Further, if there is a gateway involved, this will add in an additional hop to the PowerBI service.
Do the reports compete for a database or API resource? What happens if you schedule one for 10:00 and one for 10:30 to see if there are any race conditions in any shared sources?
How busy are the sources at 10:30 am - are there other jobs running (e.g. backups).
Try various times and combinations to see where the delays may be. If you have access to the sources, add monitoring to them to understand how they are performing.
Also keep in mind that with the recent Microsoft outages, things seem to be a bit slow at the moment at times, so if this is a recent issue then it may be transient.