Bring your own router to the site and connect directly to the 3312 (you do not have to connect to the Internet for this test). connect your laptop directly to the router if you get a flawless connection to the 3312 GUI then try the 3rd party app with your router. If this works. disconnect the customers router from the Internet and plug the 3312 directly into it with your own cables, (do not use RJ45 EZ connectors if you find any of these connectors toss them) run the same experiment. If it works, you have #1 bad / or intermittent cabling #2 a conflict with another IP based device in the home #3 you have port or other conflict with the service provider.