[SOLVED] Using Vostro 3580 with standard Ubuntu --- extremely slow Wifi uploads

I installed standard Ubuntu 16.04 on my new Dell Vostro 3580.  Everything looks great --- except for extremely low Wifi upload speeds: 

https://www.speedtest.net reports: 14ms ping, 26.66Mbps download and 0.00Mbps upload. However, there is some upload connectivity, it's just extremely slow.
By contrast, a different laptop on the same Wifi network reports: 15ms ping, 50.00Mbps download and 3.50Mbps upload.

This laptop uses the Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter [168c:0042] (rev 31) network adapter.

What can I do to fix this problem? Is there any information that I can add to make this easier to analyze?