Imagine you are a fairly wealthy individual - (say) 5 bedroom house in a couple of acres.
Someone, clearly destitute (hungry, cold etc) knocks on your door. Taking sympathy you may offer food, a bed for the night (or at least sleep in an outbuilding). The decent thing to do for another human being.
A family arrive including 2 young children. You are equally sympathetic to their need. You may let them stay a few days, and even help them access other support from the authorities - housing, schooling, healthcare etc.
A group of 20 arrive at your house a few days later - word having got out you are a generous and decent human being. You are nervous and feel somewhat threatened. You provide a warm drink, a snack, and are relieved when they go on their way.
The following week 100 arrive, including a some evidently fit young men who seem entirely capable of looking after themselves. They seem polite but the atmosphere is tense. You don't have enough food in the house, and certainly no where for them to stay. You lock the door, ask them to leave and tell their friends not to keep coming, call the police for support.
We do need to control borders - a limitless stream of migrants is untenable, unaffordable and diminishes the lot of those already here who should be our prime concern.
We should also support those in genuine need.
A balance needs to be struck between the two conflicting needs. A tough reality is that unless we are clear where that balance lies, and the means by which it can be properly managed, migrants will arrive in ever increasing numbers. We are completely lacking in both respects.