Novice Can't Connect Using Exit Node

[fwinograd]

I am very new to Tailscale and need a bit of help.
I have 2 machines. A Raspberry Pie (rp) and a Mac mini (Mac).
I want to connect the Mac to the rp which is at a remote location and use the external IP address of the rp as my Mac external IP address.

In this picture (see below) I have pasted a subset of the Tailscail Machines screen. You can see that the Mac & rp are connected.
I used SSH on the Mac and run the command "tailscale set --advertise-exit-node" on rp
The next 2 screen snaps in the picture are from the Mac.

When I do this, I no longer have internet connectivity on the Mac. What I thought I would see when I do an ipchicken.com on my Mac was the IP address the same as what I see on rp.

What am I doing wrong?

I would really appreciate some help.

[raggi]

You likely need to configure ip forwarding, the documentation for this setup is here: https://tailscale.com/kb/1103/exit-nodes?tab=linux#advertise-a-device-as-an-exit-node