Canon MX720 Series Online Manual page 190

If the radio channel of the access point is close to that of other access points nearby,
the connection performance may become unstable. Be sure to use a radio channel that
does not interfere with other access points.
• Check that the printer and the access point face each other.
Connection performance may depend on the orientations of the wireless devices.
Replace the access point and the printer in another direction to achieve the best
performance.
• Check whether other computers are not accessing the printer.
If appears in the result of the measurement, check whether other computers are not
accessing the printer.
If still appears even if you have tried the above, finish the measurement, then restart the
IJ Network Tool to start over the measurement.
Note
If any messages appear on Overall Network Performance:, move the machine and
access point as instructed to improve the performance.