Finally got this working, reporting my issues here incase someone with similar issues stumbles upon this thread.

The T54W phones would not download the xml files by https (may be because I do not have a valid certificate setup). I could via the xml files in browser on https but phones would wait awhile and fail.
I am doing auto provisioning via http, but my default admin port was set to 8080. I could not download xml files via http with admin port on 8080.
Once I changed the admin port back to default 80, I was able to download xml files via http.
Phones can now download the php/xml files via http.
I changed permissions for the php files back to rw/rw/r with owner asterisk:asterisk

Auto Provisioning was another headache. Eventually I found out that I had the config settings wrong, was using features.remote_phonebook.data.1.url instead of the correct remote_phonebook.data.1.url

My working basefile edits (using EPM):

directory_setting.remote_phone_book.enable = 1
remote_phonebook.data.1.name = Internal
remote_phonebook.data.1.url = http://<pbx-ip>/ylab.php
features.remote_phonebook.enable = 1
remote_phonebook.data.2.name = External
remote_phonebook.data.2.url = http://<pbx-ip>/cm_to_yl_ab.php

With directory_setting.remote_phone_book.enable = 1
You do not need the favorite_settings.xml to enable the remote directory. But it will put local directory as the first option and remote phonebook as the second option after hitting the directory key.

I have added this code to change the order:

directory_setting.local_directory.priority = 2
directory_setting.remote_phone_book.priority = 1

Or to get rid of the local directory

directory_setting.local_directory.enable = 0

Yealink has a Config Parameter Excel file that has all the config parameters and reading it is what lead me to find my mistake.

Finally got this working, reporting my issues here incase someone with similar issues stumbles upon this thread.

The T54W phones would not download the xml files by https (may be because I do not have a valid certificate setup). I could via the xml files in browser on https but phones would wait awhile and fail.
I am doing auto provisioning via http, but my default admin port was set to 8080. I could not download xml files via http with admin port on 8080.
Once I changed the admin port back to default 80, I was able to download xml files via http.
Phones can now download the php/xml files via http.
I changed permissions for the php files back to rw/rw/r with owner asterisk:asterisk

Auto Provisioning was another headache. Eventually I found out that I had the config settings wrong, was using features.remote_phonebook.data.1.url instead of the correct remote_phonebook.data.1.url

My working basefile edits (using EPM):

directory_setting.remote_phone_book.enable = 1
remote_phonebook.data.1.name = Internal
remote_phonebook.data.1.url = http://<pbx-ip>/ylab.php
features.remote_phonebook.enable = 1
remote_phonebook.data.2.name = External
remote_phonebook.data.2.url = http://<pbx-ip>/cm_to_yl_ab.php

With directory_setting.remote_phone_book.enable = 1
You do not need the favorite_settings.xml to enable the remote directory. But it will put local directory as the first option and remote phonebook as the second option after hitting the directory key.

I have added this code to change the order:

directory_setting.local_directory.priority = 2
directory_setting.remote_phone_book.priority = 1

Or to get rid of the local directory

directory_setting.local_directory.enable = 0

Yealink has a Config Parameter Excel file that has all the config parameters and reading it is what lead me to find my mistake.

I figured part of it out, my provisioning server is using http with authentication. I was trying to download these files from the phone with http. Switched to https and it works now.

Now I can't figure out how to auto provision the remote phonebooks into the t54w phones. I am using EPM from sangoma and editing the base config file

features.remote_phonebook.enable = 1
features.remote_phonebook.flash_time = 10800

URL and name of phonebook

remote_phonebook.data.1.url = https://192.168.1.10/ylab.php
remote_phonebook.data.1.name = Internal

That was not working and I read in yealink instructions to add this favorite_setting.xml file with remote phonebook enabled and point config to it

directory_setting.url = https://192.168.1.10/favorite_setting.xml

Still not working. When I auto provision the phone the remote phonebook setting is not enabled and the remote addresses are blank.

Is this script still working in FreePBX16?

I have this one and the similar cm_to_yl_ab.php script installed on by Freepbx server in /var/www/html/

My Freepbx server and the yealink phone are on a separate voice vlan with phones connected to vlan by LLDP. My http provisioning server on freepbx is working fine with dhcp option 66.
Initially I could not access the xml output from my native vlan, but after changing permissions to 777 for the php files I could view them in the browser and they appear to be working properly.
When I try to load them on the Yealink T54W phone either by EPM or directly through the phone GUI, I cannot get the address books to load. It thinks about it for awhile and then says failed to load address book.

What could be blocking me from loading this on the phone when it works in the browser?