On my iMac I have erased the HD using Disk Utility Recovery and am now trying to reinstall OS High Sierra. I get a popup saying, "The recovery server could not be contacted". Help please, what should I try?
Thanks Euan. That is the support page I was using when a pop-up said, "The recovery server could not be contacted". It seems that, because the HD had been erased, internet access wasn't possible until I used the ethernet cable connection. I was using start-up keys on the iMac whilst under guidance in an online chat with Apple Support, using my MacBook Pro.