HTTP POST to port 8000

Using the latest rule machine version.
Trying to post to the following but does not seem to get sent from Hubitat
https://xxx.xxx.x.xx:8000/test.json

Its like it wont post to that port. Works fine from postman from another machine on the same network.

Any ideas?

Are you sure it isn't a certificate issue? Can you try this without using https?

I think you are correct, thank you. Looks like on the post endpoint the cert is not valid.