@John-L-Clark Hmm, did see your post on PHP-FPM log just now. Looks like your setup is not handling the many requests you seem to get. How many machines with fog-client installed do you roughly have in your network?
You might need to adjust the PHP-FPM settings to your needs. Edit /etc/php/7.4/fpm/pool.d/www.conf and adjust values, then restart PHP-FPM (sudo systemctl restart php7.4-fpm).
There is a lot of information on the web on what settings might suite your setup (depending on server resources and so on):