I had similar problems with a Fanuc/GN6Mb but it was because
there was too much of a voltage drop during certain operations
such as when the spindle spools up or down, or when taking
heavy cuts or starting fast rapids.
IF you are handy (and safe) with a voltmeter, check your voltage
on the 3-phase leads coming into the machine.
The voltage on the 3 leads must be within a certain amount
of each other, plus the average reading must match whatever the
power supply on the machine is set for. (240~250, 208, etc.).
If the power being supplied to the machine is marginal because of
the total draw on your tap from the power company, the machine
can sense the voltage drop when the machine is under load and
throw the 401 alarm on all axis.
Sometmes one lead is weak (say, 5 volts lower voltage than the other two).
If this is the case, you can try swapping the leads (several possible combinations)
and test each combination by operating the machine.
I have a 10hp VMC (3-Phase) being powered by a 30hp Rotary Phase Converter off of a 115V Power Input
If you also are using a converter you may have one weak lead
as described above. It is a typical trait for Rotary Converters but
as long as your electronics are not tapping the weak lead and the
converter is large enough (rated 3X the HP) things should be OK.
Make sure all 3 axis are off of the limits when you power up,
otherwise the alarms might persist.