Port Forward: Cannot access network device from internet

I have a DVR which is connected to a router.

Router IP 192.168.1.1
Router Settings page: 192.168.1.1 Port 80
DVR IP: 192.168.1.114
DVR Video Client page: 192.168.1.114 Port 2800

Port Forwarding:
Router: Trendchip HG250
Forwarded: Port 2800 to 192.168.1.114:2800
Using the guide at portforward.com

I then checked whether the ports are open or not on http://ping.eu/port-chk/
Port 2800 is shown as open.

On the same LAN, I can access the DVR page, by pointing my browser to 192.168.1.114:2800.

My public ip is 59.xxx.xxx.xxx. When I access 59.xxx.xxx.xxx, I get my router setting page(understandable, as it is at port 80 of 192.168.1.1). However when I try to access, 59.xxx.xxx.xxx:2800, I get a "Page cannot be displayed" error.

I have tried accessing 192.168.11:2800 from within the lan, which also gives me an error. I am new to port forwarding. What am I doing wrong? How do I get to my DVR Video page on 192.168.1.114:2800, using the ip 59.xxx.xxx.xxx:2800?

I have tried disabling the firewall in the router. I have tried restarting the dvr and the router.

Note:The ip 59.x.x.x, is dynamic, current ip was confirmed before testing. dvr supports ddns, which is working at example.dyndns.org. Router page opens on example.dyndns.org,
page cannot be displayed error on example.dyndns.org:2800.

I have been through this question Cannot access apache webserver running on home network from internet which suggests disabling the router and windows firewall. In my case I have disabled the router firewall. I could not find a firewall in the DVR interface.The DVR is a CCTV DVR. Chinese make, unbranded. Model Number JA7208