PHP error: php_network_getaddresses: getaddrinfo failed: (while getting information from other site.)

It's because you can't resolve the host name Maybe DNS problems, host is unreachable...

try to use IP address instead of host name... ping this host name... nslookup it...

In the following httpd.conf file, configure the ServerName properly.

/etc/httpd/conf/httpd.conf

Like below:

ServerName 127.0.0.1:80

or

ServerName sitename

This resolved similar issue I was facing.

In my case(my machine is ubuntu 16), I append /etc/resolvconf/resolv.conf.d/base file by adding below ns lines.

nameserver 8.8.8.8
nameserver 4.2.2.1
nameserver 2001:4860:4860::8844
nameserver 2001:4860:4860::8888

then run the update script,

resolvconf -u

I would imagine that the caching DNS servers you're using aren't behaving properly (or the DNS server for the domain you're resolving isn't working properly). You can try to fix the former possibility.

Do you have at least 2 name servers registered on your network adapter? You could always swap your computer over to use a different caching DNS server to rule this out. Try Google's:

8.8.8.8
8.8.4.4

If you can discount transient outages on the remote server you are trying to connect to, then that just leaves the local network config as a problem.

Using the IP address instead of the hostname is only going to work for the default domain on the remote host.

What happens when you try using www.google.com (or its IP address)? If you stil can't connect, then its something to do with the network between your server and the outside world.