When you did the port forwarding did you do it for both TCP & UDP? I used a much earlier model of D-Link a few years ago. The control window on it looks quite different. It has option to choose both tcp & udp, however it is best to do a separate port forward for each. Make sure the port or port range is same as LW & vice-versa. Make sure Manual Port Forward setting is enabled on LW's advanced firewall setting. You said UPnP is still enabled. Manual port forward instructions & sample image. Must be same port as the one you port forwarded. Also use same port number for both Connection & Listening ports.

Oh .. something I do recall about the D-Link is you needed to reboot both the router & the computer for the changes to be properly saved & put into operation, & for the computer to recognise the changes. (But mine was an older model.)

When setting up the static ip address for the port forwarding, that process must be done first else the entire port forwarding would need to be erased & repeated. The static ip address should be similar to the router's, example: router's address @ 192.168.0.1 & your ip address at perhaps @ 192.168.0.3

No other LW's on your network may use the same port as this one you port forwarded.

You might be wise to check out tips here to get that initial connection: If LW 4 Will Not Connect (click on the blue link)