Port Forward Not Working For Myself?

It sounds like the routers are not interconnected correctly. The Ethernet cable coming from the first router needs to be plugged into a PC/LAN port on the second router. The WAN/Internet/ADSL port (whatever it is called) on the second router is not used.

DHCP needs to be disabled in the second router, and the second router needs to be given an unused address in the sub-net of the main router and preferably outside the DHCP address range of the main router. You will then have one large sub-net covering both routers.

When accessing your own server, use your internal server IP address. Some routers do not let you access servers on your own network using your public address.

Reboot everything after changing the configuration starting with the main router and working outwards across your network from there.