If you have used the transfer tool on WHM to transfer accounts to another WHM server, you might get an issue with Proxy loop on the apache settings.

Your domain might have transferred to the new server and you might even have changed the DNS, but you will receive an error something like this :

[Date] [proxy_http:error] [] (70007)The timeout specified has expired: [client x.x.x.x:xxxxx] AH01102: error reading status line from remote server host.domain.tld:80

When live Transfer feature is enabled on cPanel 90, the server will configure a proxy between the servers.

When a request is sent to the virtualhost with this proxy loop configured, it will prevent Apache from serving other requests.

When you open the apache config you can see something like the following for the corresponding virtual host entry of the domain :

<Location “/”>
 ProxyPass “domain1.com“
ProxyPreserveHost on
</Location>

cPanel has a work-around for this which you can find at

https://support.cpanel.net/hc/en-us/articles/360052634234-Transferring-an-Account-from-the-local-server-to-the-local-server-results-in-infinite-Apache-Proxy-loop-on-cPanel-90

I had deleted those proxy lines manually, before i saw this post from them.

Hope this helps someone.