What's the hardware version of your W8968?
The internet server is using port 80? What's the IP address of it?
On web interface of W8968, you can go to NAT-virtual servers to configure it.

Vivian wrote

What's the hardware version of your W8968?
The internet server is using port 80? What's the IP address of it?
On web interface of W8968, you can go to NAT-virtual servers to configure it.

Thanks for answering. The hardware version number is 3.0. On my LAN I have a couple of machines with webservers on them. I don't think the IP addresses are important, but they are 192.168.2.102 and 192.168.2.104. I have the old Belkin router set up like in the image below and I want to do the same on the TP-Link but can't get it to do what I want. Any ideas?

You should go to NAT---Virual Servers to configure it.
Inbound port and Private port on your old router are called external port and internal port on W8968 V3...
By the way, did you enable remote access for your W8968?

Thanks Vivian, I was being stupid, I've got the port forwarding working now. I have enable remove access, which meant I couldn't use incoming port 80, so I've moved that one to another port. Actually, even without enabling remote access, it still wouldn't let me use incoming port 80, not sure why?

One other question - I'm having difficulty getting the router to update dynamic DNS. I have a pro account with dyndns, I've set up my hostname, username and password in the router, but it's not updating dyn.com with the current IP address. Any ideas?

Port 80 is the web management port which cannot be changed.
Can you use a different external port like 8081 corresponding to internal port 80?

Yes, I'll use a different external port.