"My last stress test was to check for interaction with USB 3.0 storage. Routers with USB 3.0 ports must take care with internal design and shielding to prevent impairing 2.4 GHz radio performance (and vice-versa) when both are active. ASUS' RT-AC68U is an example of poor USB 3.0 port design. In our retest, the AC68U's USB 3.0 port storage throughput looked the same as USB 2.0 with the Reducing USB 3.0 interference setting disabled.
ASUS moved the USB 3.0 port to a front corner of the AC87 and this design looks successful. In the First Look, I found filecopy performance using the USB 3.0 port was much improved with 50 MB/s writes and almost 70 MB/s reads.
For this test, I used a different computer and test file than used for the First Look Filecopy tests, so results are different. The screenshot below shows a drag-and-drop filecopy of a single 1.15 GB Windows backup file from the computer connected to the AC87's LAN side to a WD Passport USB 3.0 drive shared by the AC87 as an NTFS formatted folder."