Hi, Sizo.
The NoContent (204) return code is generally sent when 1) the URL being accessed is considered to be invalid for some reason, 2) the user-agent of the client doesn't match our requirements or 3) when the Enrollment Server is unable to reach the database server.
You mentioned that the SSP enrollment worked. If this is SP5, can you verify that the enrollment policy linked to your SSP via the Server > Configuration > Component \ Self-Service Portal config page is the same enrollment policy that you're using and that there's only one enrollment code in that policy?
If this is SP4, please check the Web.config in that specific SSP's installation path and verify the enrollment code defined for Android is the same code you're using.
If the code for the SSP matches what you're trying manually and it works through the SSP but not when manually entered, it's likely going to take deeper troubleshooting than a forum post, unfortunately. So I would request you open a support incident, in that case.
Before opening the incident, after verifying the codes match, try once more to enroll via the SSP just to be sure it still works. If you are now in a situation where neither works then the circumstances will have changed and it would be good to look at everything again.
Thanks,
Keith Nunn
SAP Active Global Support
SAP Canada