Constant alarms outside of my motion zone

We live in a rural area with many passing large farm vehicles 18 hours a day. Because of this I have set up 1 zone that should only alarm when someone comes through the gate onto my property. However we are constantly awakened by the ring doorbell almost everytime a large vehicle passes and they are nowhere near the zone I have created. The doorbell is 1.6m above the door threshold, it is north facing therefore not subject to any sunlight, reflections etc plus this happens during dark periods. Absolutely driving us crazy to the point I want to get rid of it. I have changed settings multiple times but to no avail.