I managed to find where the problem was. One of the services snatched port 80, before traefik. To find the thief, I used this command:
kubectl get pods -A -o jsonpath='{range .items[*]}{.metadata.namespace}{" "}{.metadata.name}{" "}{.spec.containers[*].ports[*].hostPort}{"\n"}{end}' | grep -E ' 80| 443'