7i96s: can't seem to get a stepper enable signal

yes it's enable-in not estop-in ie make true to enable. I agree bad naming.

yes the top left estop button.
If it doesn't toggle you must check all those pins/signals again.
If iocontrol.0.emc-enable-in changes state the button will toggle.

OK, it seems that axis needs to be restarted to make this happen, but it does. I.e., when the switch is closed, it is possible to enable the stepper motors, at least according to the icons. I have yet to test whether there is an actual enable signal coming out of the board, but before the watchdog bites, the LED for the output turns on. This seem like a good thing.

I have checked the invert checkbox for the ESTOP input so that the rest of the logic functions correctly. So, progress.

Thanks. Now to figure out what causes the watchdog to bite. It could be that I have this web browser open. Average ping delays of about 0.5 ms probably don't help either, but I can't imagine how to make them better.

You can run the servo thread at a lower speed (at least until the Ethernet latency issue is resolved)

You might try 2 ms (2000000 ns)

If you change this, you also need to change all the PID P terms to 500.