The easiest way to check your server php info is to install the WordPress plugin.
For example it could be WordPress phpinfo() plugin.
Alternatively you can follow the instructions in the WordPress’ Knowledge Base – Finding Server Info
Yous should manually create a file near your wp-config.php called “phpinfo-871345410.php”, then paste the following code into it and save the file:
After that to see your php info you should open the following address in your webbrowser: http://your-site.com/phpinfo-871345410.php
Warning: the php info contains technical information of your server which you don’t want to share with the world. So after checking php info and sending some information to support you should delete it. You can re-create it again in case of need at any moment.