@more75 

Can you please provide the detailed network layout, how are the two routers connected to the network? Is it like below?

main router 192.168.1.1(LAN)----(WAN)TL-WR940N(LAN)----camera

If yes, you need to open the 36666 port on both routers, check the below guide to open the port for the camera on the WR940N:

https://www.tp-link.com/support/faq/1379/

After that, you need to open the same port for the WAN IP address of the WR940N with the port 36666 on the main router, then you should be able to access the camera from an outside network.

@more75 

192.168.1.81 is the WAN IP address of the WR940N, right?

Open the port 39999 and 95 for the IP 192.168.0.93 on the WR940N, you can refer to the instructions I provided to you earlier.

Then open the port 39999 and 95 for the IP 192.168.1.81 on the main router, as per the port forwarding instructions on the main router, you may need to check with the resource of the brand and model for the router, or you can ask on their community.

@more75 

Is the WAN connection type on the WR940N static IP or L2TP? And the WAN IP address is 192.168.1.81? Try to open the 95 and 36666 ports on your main router for the IP 192.168.1.81, then check again. Please ensure the port forwarding setting on your main router is correct, confirm with the router support if you are not sure about it.