Default Screen mirror issue s4

Hi guys

So I have an s4 and an s5. Both 4.4.2 and both rooted. I connect to a Samsung TV with screen mirror and they generally connect ok. I then launch a VPN client to get to Netflix US and as soon as i do this this it will disconnect the screen mirror. Tried a few VPN clients. I think i read before about this but cant find the link. This does not happen using a rooted s3 though so im guessing its not the fw on the TV. Any help would be much appreciated as i cant sell my s3 until i get the screen mirror working properly on the s4 or s5