Unable to reinstall macOS High Sierra on 2017 iMac after erasing Macintosh HD

We recognize you what to revert the computer to its original version of macOS

But, for sometime now, the macOS 10.13 High Sierra seems to have been removed the the Apple Recovery Servers

An iMac is a 21.5 inch 2017 can run macOS 13 Ventura at best

You will need a stable and reliable international connection so suggest using an Ethernet connection to your Router

This would avoid the iffy Wifi connection

Pressing Option-Command-R on an Intel-based Mac starts up into macOS Recovery over the internet, allowing you to reinstall the latest compatible version of macOS.

uzoma209 wrote:

Yes instructions would help a lot

See my post here with instructions for creating & using a Knoppix Linux USB stick.

Creating & Using a Bootable Knoppix Linux USB Stick -- @HWTech - Apple Community

Make sure to post the complete GSmartControl report. You need to use the "View Output" or "Save As" buttons to see the full report. The latter may be the better option for Copying & Pasting the report here.

uzoma209 wrote:

Alright so I just checked out the article but I came across another problem when I try to boot the high Sierra recovery mode after the timer my screen always freezes on the Apple logo

More than likely the internal Hard Drive is failing. I did previously post a link to the instructions for creating & using a bootable Knoppix Linux USB stick to check the health of the Hard Drive. You can also try installing macOS onto an external USB drive as well to use a macOS third party app to check the health as well.

and when I enter recovery through the oldest version of OS my it won’t allow me to reinstall from OS X, so not sure what to do about this.

It really helps to have specific details on how it won't allow you to reinstall an older version of OS X.

My guess is you must first partition & erase the whole physical drive (or just the Fusion Drive part if your iMac has a Fusion Drive) since macOS 10.13 High Sierra would have used a different drive layout & file system unknown to the older versions of macOS. Here are the instructions to partition & format the Hard Drive (or Fusion Drive) in the following article:

https://eshop.macsales.com/tech_center/formatting/Mac_Formatting_6-10_R3.pdf

It is likely that the internal Hard Drive is worn out or failing. You can try installing macOS to an external USB3 SSD to compare results.

You can also try running the Apple Diagnostics to see if any hardware issues are detected, but unfortunately the diagnostics will rarely reveal a failing Hard Drive.

uzoma209 wrote:

also when I try to use the recovery that takes you to the most recent OS when I try to re install it there it says unable to contact Apple servers.

uzoma209 wrote:

Can you not help out if it’s a 2011?

Use Command + Option + R to boot to the online macOS High Sierra installer. You will need to use Fix #3 in the following article:

https://mrmacintosh.com/how-to-fix-the-recovery-server-could-not-be-contacted-error-high-sierra-recovery-is-still-online-but-broken/

I would also like to repeat my earlier diagnosis that most likely the internal Hard Drive is failing which is why it is so slow. Unfortunately booting macOS from an external USB drive is not a good option an easy way to keep using the iMac if the internal Hard Drive is failing due to the extremely slow USB2 ports on a 2011 Mac.

I do have a relatively easy method of checking the health of the internal Hard Drive which involves creating & using a Knoppix Linux USB stick which contains a utility that can retrieve the health information from the Hard Drive to confirm its health status. You can also try running the Apple Diagnostics as well....if it reports an issue with the internal Hard Drive, then it confirms the drive is bad. However, a passing diagnostic result does not necessarily mean the drive is healthy...the Knoppix USB stick is the best method of confirming the drive's health (not 100%, but 90%+ accuracy when interpreting the drive's health information). I can provide instructions if you are interested.

uzoma209 wrote:

Im not sure why but when I go into recovery using Option-Command-R regardless it still takes me to high sierra and I’m not sure how to go about this

Let us establish the actual age of this " My Mac is a 21.5 inch 2017 "

About this Mac will define the age of this computer

uzoma209 wrote:

Im not sure why but when I go into recovery using Option-Command-R regardless it still takes me to high sierra and I’m not sure how to go about this

Unfortunately some Macs do this regardless of the startup keys used.