n600 c3700 usb port question - previous answer incomplete

Thanks for the links.  They do help. 

Unfortunately, there are still quite a few qualifications, such as "If you want to use a USB drive larger than 2 TB, you might need to format the drive into partitions smaller than 2 TB (for example, you might need to format a 4 TB drive into two 2 TB partitions).".  This article doesn't actually say which routers have this limit, it appears to be quite old.

Both of these articles appear to apply to very old devices; the largest drive listed in the first article is 4 GB, which is 8 to 10 years out-of-date.

At least the articles say that USB 3.0 drives are backwards compatible in at least some circumstances  ( the C3700 manual says it's USB 2.0).

Some other routers will work with drives up to 8 TB, but they don't say if that's one partition or multiple partitions, and I don't know if the other routers are newer or older than the C3700.  Since my friend bought the C3700 recently, it is hopefully one of the newer models.

Apparently, the best Netgear can do is tell us to experiment with the drive, and hope it works.

Perhaps we (the community) will have to compile a list of drives on our own that will work.  I can state that a Seagate SRD00F1 2 TB drive with a single partition, MBR partition  and NTFS file system will work and can be powered by the C3700.