Overview
When trying to create a custom report for subnets, if the range is greater than that of two weeks prior, the following error may occur:
Error: Daily granularity for Subnet statistics is only available for the past 2 weeks. Monthly granularity is available for older data.
Root Cause
When creating a report for subnets, any date further than two weeks ago can only use monthly granularity, which means only entire months (e.g., May 1st to June 1st) can be added to the report, not days or weeks.
The same ideology applies to the web UI, which grays out the dates that cannot be chosen to make a report from. It does not generate an error because there is no possibility of accidentally selecting the dates.
Resolution
Change the date range of the custom Subnet report to be a full month.