Monitoring tailscale with uptime kuma

I am trying to monitor my Tailscale server, running on a RPi

A little info on my setup…

I have a raspberry pi running pihole, and Tailscale (same Pi)

I have a second Pi running home assistant.

The second Pi runs Home Assistant OS, with the Kuma add on, and the tailscale addon.

I can monitor other services with Kuma, for example zigbee2mqtt via a TCP port monitor, or the pihole itself via a ping monitor.

When i try to set up a Tailscale Ping monitor, it is constantly showing as down.

Im sure I am missing something in how i have it set up, but if anyone can offer any help / guidance, itd be most appreciated