Please, check your logs and see if you can find a clue about what is causing this downtines and errors.
You can reinstall Webinoly doing an update sudo webinoly -update, another option is reinstalling using the option "0". Both will overwrite files.
Another option is the "server reset" command sudo webinoly -server-reset
Please, try this:
Increase the "fastcgi_read_timeout" value in /etc/nginx/conf.d/fastcgi.conf. Current value is 30, maybe try with 120 and tell me if it solves your issue.
Don't forger restart nginx: sudo service nginx reload
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