Configure MDM Server for iPhone

First up, the 405 status from the server means that you are attempting to POST to a URL that does not accept the POST method. It has nothing to do with the certificates at this point. The certificate in MDM is only used for signing the MDM messages so anything that is put in there is unused if you are not signing your MDM messages from the device (I would recommend not signing your MDM messages while you are testing/setting up) which is configured using the 'Sign Messages' tick-box in the iPCU.

The general idea with MDM is that you tell the device to 'phone home' to the 'Server URL' configured in the configuration profile when it receives an MDM APNS message. You will either have to write or purchase the code that lives on this server to respond to the device and do the right thing. You can also configure the 'Check In' and 'Check Out' URLs to talk to different URLs and, therefore, different code components on the server to handle the different messages.

You need just 3 things

1) mdm payload with mdm url starting with https://
2) certificate which you download using apple developer portal. This is detailed on apple site
3) Link this certificate (.p12) file in the identity section of the mdm payload

Your server needs to have the necessary ports open - this is also documented. The server needs to listen on PUT method and not GET or POST.

If you do above - you will see that your device sends the deviceToken, pushMagic etc.