Correctly adding one-time SDT via API?

So I'm trying to add a one-time device sdt in Postman.. I get getting an error return of: endDateTime should be a future time

I've tried incrementing the end time value by 100ms, by a few thousand then lastly I jumped probably a year ahead, nothing works.

Here is the payload:

{

"type": "DeviceSDT",

"sdtType": "1",

"comment": "test sdt from Postman",

"deviceDisplayName": "host1.domain.net",

"startDateTime": "1714753638",

"endDateTime": "1724755900"

}

The example payloads, while is in a Python script, are the same as mine, I just don't get it.