Setting up Tailscale with Let’s Encrypt. Banging my head against the wall

I feel like I'm missing something so basic it's blinding me. I can't for the life of me make this work.

I've had Tailscale up and running with Ubuntu, Windows, Rpi's etc. All happy. Everyone/everything works as expected. Looking to implement https to the environment.

I'm following several videos, Alex's included on setting up Let's Encrypt to work on machines in my tailnet and I continue to get the error on the browser indicating the cert / https connection isn't working.

Following step by step the outline here: https://tailscale.com/docs/how-to/set-up-https-certificates

Environment:
Windows11 machine running Jellyfin with tailscale running.
Have Magic DNS enabled.
Have https enabled in my TS control panel.
Performed 'tailscale cert myjellyfinmachine.my.tailnet-name.ts.net' and it returns 15-ish seconds later with "wrote public cert to …. etc."

However when I open a browser I can't get to the https flavor of the server. I can access it via my TS ip address and domain name, but not via https.

Browser returns:
"Secure Connection Failed
An error occurred during a connection to jellyfin.xxx.xxx.ts-.net:8096. SSL received a record that exceeded the maximum permissible length"

Have reviewed the docs again and again.

Anyone have any direction on how to diagnose further or better yet, resolve / what to look for?

Appreciate any info/input/suggestions.