importing data in excel from external source and autorefresh every 15 min. enabled but not getting data refreshed

[adpatel]

I have imported data from external source, that data gets automatic refresh after 15 minutes I have such 10 sheets in one workbook.
when I am trying for 5 sheets it works very well but when i try for 10 sheets in one workbook it just shows "connecting to web" and does nothing.
kindly help with this issue. thx in advance