Probably need more detail….these are all the things I would check if I ran across a similar problem.

How many records in the quick report?

When doing the export, what is the Output format?

Do other reports export fine following the same method?

Has this report ever worked for export?

Have you tried modifying the report parameters to limit the dataset to ensure a small number of records works ok?

Have you tried running the same query from SQL Query Tool and exporting the records from there?

One of your questions got me thinking.  “How many records in the quick report?”  While I have a parameter in the quick report to give me GL records for a given month, the report is based on a custom view which I did not write.  That custom view did not have any time limits so it was producing a dataset with millions of records causing IFS to time out.  I modified the custom view to only look for current year records and all works fine now.

The Quick report view only return a set number of records so I did not see the timeout there, only on the export to excel.

Cool, yeah running the quick report is only going to return the first few hundred records until you scroll down.  Exporting has to run the whole list.  The timeout is usually an indication of records in the millions. 

Other checks are to sub Count(*) into the query just to see what you are getting or use Ctrl-End on the quick report to force IFS to run to the bottom.