Just saw this error and usually this is due to having a misconfiguration in the database connection options. But I am running Fedora 25 with seLinux enabled by default.
First to test if it’s seLinux causing an issue
sudo setenforce 0
If it works fine with seLinux disabled then do the following:
sudo setsebool -P httpd_can_network_connect 1 # turn seLinux back on sudo setenforce 1
Should now work