For some reason you can't access proxied server on localhost address and get an error like:

[Wed Sep 17 13:50:40.031673 2025] [proxy:error] [pid 12350:tid 139861767968512] (13)Permission denied: AH00957: HTTP: attempt to connect to 127.0.0.1:3002 (127.0.0.1) failed
[Wed Sep 17 13:50:40.031875 2025] [proxy:error] [pid 12350:tid 139861767968512] AH00959: ap_proxy_connect_backend disabling worker for (127.0.0.1) for 60s
[Wed Sep 17 13:50:40.032054 2025] [proxy_http:error] [pid 12350:tid 139861767968512] [client 51.83.244.185:48488] AH01114: HTTP: failed to make connection to backend: 127.0.0.1

Permission denied is caused by selinux. Solution is to run:

/usr/sbin/setsebool -P httpd_can_network_connect 1

• CentOS 7

• https://stackoverflow.com/a/28201422/6881647