The last line of /etc/php/php-fpm.conf is where the 8 MB value is set. But it is not that simple…if you edit this file and reboot EX2, that file gets overwritten by a fresh, pristine copy from the firmware (which would match the original one you just edited thus wiping all your edit). The only quick and easy approach to make an edited php conf to work might be to kill the php master process (and possibly the child processes if they’re not auto-killed with the master php process) and then restart php-fpm process, without rebooting the EX2. But it might work…it might not…in which case you may have to resort to a more intrepid hack…which is to mod it in the firmware code and then rebuild the firmware and of course that would technically void your warranty.