winrm quickconfig -2144108269 0x80338113 error

Got dragged by a user into an online chat today about a winrm issue. Couldn't find a solution online after rounds of "googling". But finally figured out the problem. Post it below, hope it helps if you are in the same situation-

Symptom:
Users have two winrm server hosts, and not able to run "winrm quickconfig" on either. One of the host is new, so they never run winrm there before. But the other host, users were able to run "winrm quickconfig" a while ago and were able to setup the winrm http  & https listeners there. But now although they can still use "winrm e winrm/config/listener -r:<winrm_server_host>" to see the winrm listener setting from a client host, on the winrm server host itself, they see the following error whenever they run "winrm quickconfig" -
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C:\Users>winrm quickconfig
WinRM already is set up to receive requests on this machine.
WSManFault
            Message = The WinRM client sent a request to an HTTP server and got a response saying the requested HTTP URL was not available. This is usually returned by a HTTP server that does not support the WS-Management protocol.

Error number:  -2144108269 0x80338113
==============================

Investigation:
Checked "winrm get winrm/config -r:<winrm_server_host>" from a remote machine. And all looked fine.
Checked "winrm e winrm/config/listener -r:<winrm_server_host>" from a remote machine. All looked fine too, except that besides "127.0.0.1" and "::1", there were two other ips for the host (which usually is only one ip). Turned out that this was not an issue, because the host had 2 nic cards.
But the two ip addresses prompted me to ask the user if there's anything unusual or if anything had been changed in the hosts file. And user realized that an entry for "localhost" had been recently  added to the "etc\hosts" file, which had changed the ip for "localhost" from default 127.0.0.1 to the host's ipv4 address.

Resolution:
Had user comment out the localhost "redirect" line in the etc\hosts file. And user was then able to run the "winrm quickconfig" on the winrm server host without error.