when I install a k3s cluster with n nodes all nodes IPs shoud respond to the port 80 and 443 of traefik ?

if they all have 80 and 443 available. You can see what nodes were available to host the servicelb pods if you do

kubectl get service -n kube-system traefik

and look at the external-ip column. If you don’t see one of your nodes IPs listed there, check to see what prevented the daemonset from scheduling a servicelb pod onto that node.