Excel 2016 PivotTable report may generate an error message after running the report for 1 minute.
The connection timeout was exceeded.
This problem only happens if you have the build number 11.0.9167.412 of the SSAS OLE DB Provider shipped in Excel 2016 update. You can check the following files and see if the version is build 9167.
C:\Program Files (x86)\Microsoft Office\root\VFS\ProgramFilesX86\Microsoft Analysis Services\AS OLEDB\110\msolap110.dll for 32-bit
C:\Program Files\Microsoft Office\root\VFS\ProgramFilesX64\Microsoft Analysis Services\AS OLEDB\110\msolap110.dll for 64-bit
If I replace this dll from an earlier version, for example, build 11.0.9166.514, then the problem is resolved.
This is a known problem, and the dev team is investigating the cause and the fix. I expect a fix should come soon in an Excel update.
Excel 2013 does not have this problem.
The fix will be in July's Current Channel/Insider's Channel Office 365 update release.