Unfortunately the European ideal of free movement has always been flawed.
For example letting hundreds of thousands of refugees, migrants etc head unimpeded across Europe was a disaster waiting to happen with the risk of infiltration by criminals bent on creating havoc. You then end up with ghettos like the Calais one which no-one seems able to sort out.
Whilst appreciating the needs of desperate, innocent people we need to start significantly reinforcing border controls and set about removing people who shouldn’t be here. Security starts at home.