Connection to board was lost

[dudo02]

Hello,

I would like to ask for help.

When I connect to LK from inside network ,everything is OK.
When I connect from internet, everytime same error "connection to board was lost".

At my home working everything fine , but in my Client house in his network still same error when I try connect from internet.
So it is looks like a problem with network, but when I use same settings(IP,PORT FORWARD) for another device(camera system) ,everything working fine.

I read few topics about this problem, but did not find help - my polish is poor.

Hardware 1.2.
I tried few firmwares,but still same problem.

[dudo02]

Problem solved.
There was something wrong with router TL-WR340G from TP-LINK.
After router replacing everythink OK.