Thank you for your post.
That long number is the IPv6 IP Address. The short one is your IPv4 IP Address.
The long IPv6 IP Address can be turned off. Go into System Preferences, click on Network, select "Built-in Ethernet", and click "Advanced...", In the next screen, you will see your short IPv4 IP Address, and in the lower half, your long IPv6 Address. In the pop-up next to "Configure IPv6", change this to "Off". All other machines will need to do this, too.