[SOLVED] Difficulty With Minecraft Server

This is another "cant create a Minecraft server" post ... I hope someone is able to help. The server is working on my computer but it is not working on his.

Our computers are connected via Ethernet cable directly to the ASUS RT–AC86U router. szv7 of his local computer is 192.168.50.166.

The port forwarding settings are:

Service Name: Minecraft Source IP: (blank) Port Range: 25565 Local IP: 192.168.50.166 Local Port: TCP: 25565 BOTH

He connects to 192.168.50.166 when he is running Minecraft on his personal computer. If you enter an external IP (obtained via the "Network Map" page in the router settings) it will return the error:

Failed to connect to the server io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection timed out: no further information

When I attempt to connect from my computer to 192.168.50.166, I get the exact same error message from Minecraft.

Here's the best part: If I run the server on MY computer (192.168.50.48) and alter the Local IP port forward settings in accordance with the settings, everything works. I can connect to the Minecraft server with either my local IP or the external IP.