I have been experiencing this weird memory issue with firewalls running on the 18.104.22.168-53n code . Having a few TZ500 & a NSa 2650 running on that code. Memory keeps on increasing on a daily basis until 98-99% ultimately resulting in the firewall rebooting. The problem here is there are no users logged in or many things going on with the firewall that justifies high memory utilization. I remember upgrading them from 22.214.171.124-6n to get rid of the high CPU utilization problem.
Has anybody else been experiencing similar issues (see attached memory utilization trends) ? Need some help as I don't want the same thing to occur when I upgrade them to the latest code.