Yesterday, I finally grounded both the guy wire and the DSM.  However, I forgot that I had noticed the DSM being down and staying down the day before.  Thus, the DSM stayed down all day. The Ubiquiti was up and connected, according to the LEDs.  I also yesterday noticed an issue when I couldn't ping anything on our Marshall wifi network for an hour or so in the afternoon.  This problem went away later on.

This morning, I found the console port on the Pi to be unresponsive, so I did a power reboot to the DSM.  Everything seemed to come up okay, and we are getting ncharts data again.

As an additional precaution, I adjusted the Ubiquiti azimuth to point east of the station adaptor, to give it more beam separation from SPol.  I still had the full (4?) LED signal strength indicator.  With a ~30-degree half beam width for the NanoBeam, it still will see some SPol signal.

SPol ran briefly (one complete scan) while I was there and the DSM stayed up, but I don't know if SPol was transmitting.  We'll keep monitoring...