When you experience that vacuum hold-down is insufficient or pieces are moving while cutting, there are some ways to improve your vacuum.
Make sure the correct vacuum zones are opened and closed.
Cover table top
Cover the active vacuum zone as much as possible with non-porous material, preferably sheets of plastic.
If the material is moving during routing or cutting, if possible, replace the sheet of material with a bigger one. The larger your piece of material, the more active contact it has with the table top and so the vacuum. If it is not possible to replace the material, try to fix the sheet with tape or place other pieces next to it.
When routing, use wash-out functions instead of cutting loose small parts. It is often advantageous to reduce the chip waste/ debris vacuum by letting in "false air", either by locking the toolhead suction house in a lifted position or on newer machines that are equipped with a such open the Air Reduction valve.
If your machine is not equipped with the Air Reduction valve, it can be bought as a Milling Accessory in the Esko Store.
Check that the tubing from the vacuum pump to your table top has no leakages. Do you hear any abnormal sound? Look for places where there might be a loss of vacuum. Check if the tubes are well connected to the table top. Also, avoid to place the vacuum pump too far away from the machine and avoid too many corners in your tubing. Every meter of tubing and every corner will cause a loss of vacuum efficiency. Avoid corners of 90° or more.