@JamesBorne That was rude. The purpose of a forum is to post common or edge-case problems, and document the exact solutions for the benefit of others. We don't all have to be PHP experts to use FusionPBX. Don't reduce this forum to belittlement of others.
@Chazoo15 I find the default 24 minute timeout frustrating too. Here are the exact steps I took to change timeout to 8 hours.
Bash:
$ nano /etc/php/7.1/fpm/php.ini
session.gc_maxlifetime = 28800
$ systemctl restart php7.1-fpm.service
Granted, once you are done doing heavy testing and will be using the portal less, you might want to drop that back to the default 24 minute timeout (1440 seconds)