There is so many articles regarding how to configure the Lync Edge Server but it was really hard to find out or none of articles show right information regarding the "Push Notification" for Apple devices and Windows devices.
I found out that Push notification requires Public SRV records.
Once these are configured, please look at Lync FE Server
That is all!!! Simple thing but easily can messed up!
Make sure Internal and External CA installed on Edge Server, root CA has to install to trust Internal Domain as well.