AVTECH AVC776W: Want to watch the live feed through the Video Web Server: LAN error

HI,

I have a really annoying problem with our AVTECH AVC776W Digital Video Recorder.I would like to watch the live feed through the Video Web Server software,but it's working only in LAN,i can't watch it from home.Everything was set up correctly.After that the lan was crashed also.I made a hardware reset,the LAN came back,but i can't see it via internet.What could be wrong? I'm a technician and our customer is nervous a bit... I would thank for any help.