I have successfully installed NoDogsplash captive portal on ubuntu 16.04 and it's working fine when the device is connected to LAN. Now the issue is when the device is not connected to LAN, NoDogSplash is not working and devices are not able to connect to AP or if they made a successful connection then redirection doesn't work.
Also noticed that while not connected to LAN, NoDogsplash is eating 100% CPU.