Does the forum logs give an error when it crashes?
Do you have mongo and nginx logs on?
There should be some useful information in one of the logs as to what is happening.
Here are warning from the FF Web console while browsing my site and this site. They are minor compared to what Chrome's Web console reports.
Use of getPreventDefault() is deprecated. Use defaultPrevented instead. nodebb.min.js:2 Empty string passed to getElementById(). nodebb.min.js:1
Will need you to try again in dev mode, as those errors are reporting the minified line count (which is always 1)
Those warnings are not just from my site, but from this site also.
Yeah these are jQuery/bootstrap errors, only happens in FF, and unfortunately not something that will be fixed unless we migrate to the latest jQuery (which also means we'd have to drop support for IE8). Not a big deal imo, it doesn't affect anything aside from annoy me a little when I'm debugging code