FreePBX Remote PhoneBook issues

[Sergey_Lagger]

The phone shows up with this error message when I try to open the remote phonebook from the Yealink phone:
Fail to download remote phonebook
We are having issues with adding the remote directory from Contact Manager to Yealink phones

We have done the following:
I have followed through the below guidance:
https://community.spiceworks.com/topic/2280042-freepbx-moved-to-new-host-now-yealink-phones-can-t-do…

and through the following one:
https://mangolassi.it/topic/18647/freepbx-contact-manager-to-yealink-address-book

we have given ownership to asterisk in the following location
/var/www/html/ylab.php

have opened the TFTP port

UTF-8 encoding for php and xml files
tried the following remote URLs:
https://ipaddress/cm_to_yl_ab.php
http://ipaddress/cm_to_yl_ab.php

converted files into xml and put them into Remote URL as:
http://ipaddress/cm_to_yl_ab.xml

https://ipaddress/cm_to_yl_ab.xml

The links are opening without any issues from the web on the laptop/PC which are on the same network
Also, we have tried creating the contact list with just a few contacts, because we have more than 18 000 contacts in the original one, it was having the same error message on phones.
P.S. the Yealink phones are registered, seems like there is something inherently blocking the phones to the PBXs as we can confirm the script runs via the browser.

Please let us know if you had this issue before or if you might know what is blocking the phones to open those remote phonebooks