I have a very strange issue and I ran out of ideas. The major problem is that the symptoms are not consistent.
I have a short link website hosted on 2 virtual machines, one with nginx+php-fpm and one with the database. The script has an basic API and a wrapper for some services to use.
Now the strange part:
If I do a curl on the server the get the site domain it works, however if I do a curl to the api link that has the format
http://domain/api/v1/APIKEY/shorturl/create/url/aHR0cDovL3d3dy5nZ2Fmc2EuY29t.json (the last part is the link encoded) I get an empty response. If I check the same link from my browser it works fine.
Since the wrapper will get some variables and pass them to the link above internally and the curl for that link is not working on the server the wrapper is returning an error.
The firewall is empty, I disabled entirely cloudflare (changed ns) to make sure it's not a cache issue, disabled nginx cache, disabled opcache settings in php.ini.
Since the symptoms are inconsistent I can't tell where the issue is coming from and to be honest I kind of ran out of ideas.
Any help or suggestion is appreciated.