I have a Shell script which is named "dns.sh" which changes the nameserver in /etc/resolv.conf.
it looks like: 
#!/bin/bash

echo nameserver 127.0.0.1 | sudo tee /etc/resolv.conf

Problem is, if i make a autostart instantly after login through lightdm, then captive portals wont work... Pretty annoying. How can i let this script autostart like after 20-30seconds ?