Good day everyone! 
  
I just need a help regarding dahua manage layer 2 switch model PFS4220-16P-250. 30 cameras 4MP with optimum/ default settings then the result was lagging. 
  
switch location are in different building, distances each switch is around 70-80 meters. 
  
I'm a bit newbie on networking and confuse on  how to properly connect these switches in trunk mode to distribute bandwidth. 
  
3 switches are plugged in in link/act gigabit ports. port number 17 or 19. 
  
anyone can help me would be appreciated. Thank you!