Unable to upgrade to macOS High Sierra

I'm trying to upgrade my mid-2010 iMac to High Sierra so that I am able to download Logic for my home studio. It requires 10.13.6 or later and mine is currently using 10.12.6. I have tried the installation but it continues to give me an error saying "The recovery server cannot be contacted" and won't continue any farther. I've tried several of the fixes people had mentioned in different forums and nothing is working. Is there anything I can do? Please help!