Problems with samsung galaxy grand prime and remote acces.

Hey everyone, this is my first thread in the forum. I installed a CCTV system and configure a DDNS via NO-IP webpage. The thing now is, I've got the remote acces to work on 6 android phones, but cant make it work with 2 Samsung Galaxy Gran Prime phones. Any ideas what might be the problem? the APP im using is VmEYE.
Sorry for bad english.

Bye everyone~