Watchnet on internet problems

Hi all

I really need help, I dont know where to ask, I have a client who have a watchnet DVR, very weird problem, i forwarded all ports to access the dvr on internet, 4000-4001-8080 thats ok, all the ports are open, im using ie8 with low security, i can only access the camera webpage with my shared cellphone internet connexion, if i use it with with my ISP connection, that doestn work, I tried at my friend house, not working, at my job, not working, in my sister house, not working, all is different ISP, tried with 2laptop, the minute i plug my cellphone internet connexion on the two laptop, thats working. I rebooted all is equipement.

Anyone can help or saw the same problem please .

Thank you!