It looks like there is no single port that is for uplinking:

H. Connections to Wired Computers – Gray (the grey colored ports)

Connect your wired (non-wireless) computers to these ports. These
ports are RJ45, 10/100 auto-negotiation, auto-uplinking ports for
standard UTP category 5 or 6 Ethernet cable. The ports are labeled 1
through 4.

Try switching to another port on the router or try trading the ports that you and Kidd are using and see what happens.