Uptime Kuma referencing Tailscale server names

This might be a n00B question, but here’s my current setup:

Uptime Kuma running as an HA Add-on
Tailscale running in HA as an Add-on and also on the server that houses HA

I would like to set up an Uptime Kuma monitor that Pings a server using a Tailscale Name. However, it appears that Kuma doesn’t recognize Tailscale DNS (or it fails for a different reason). I am, however, able to use a Tailscale IP address … which doesn’t make a lot of sense to me.

I can’t use the name or the full name (e.g. xxx.ts.net) just the ip address.
Anyone have any ideas as I don’t think I can rely on my IP address to stay static (it’s within a Docker instance).