I knew there was a problem with File Sharing in the new High Sierra OS. I had read about it on other Mac sites. A short time after upgrading my Late 2012 iMac to High Sierra, I encountered this network problem first hand. Here is how you fix it.
File Sharing SMB
Apple has decided to deprecate their old AFP file sharing protocol. They are going with the SMB (Server Message Block) format which is pretty much the industry standard.
I send files to my wife’s MacBook Air over our network all the time. Just have to click on her machine in the Finder and login. However, the first time I tried to access her Air in High Sierra I got this error message:
It was then I remembered the articles on AFP and SMB. To fix this issue, first go into the Sharing Preference Pane:
Once in the Sharing Pref Pane, click on “File Sharing” in the left sidebar:
Then click on “Options” and you will get the drop down window:
Your setup may have different options. Both SMB and AFP may be checked or perhaps just AFP. In any case you need to uncheck AFP and leave SMB checked. Then click Done and you are all set.
I have one final comment that is very important. The first time I did this, File Sharing still did not work to my wife’s Air. I did some troubleshooting on her machine and discovered it was still set to AFP. Any the machines you are connecting to must be set to SMB with AFP turned off. When I did this on the Air, everything worked like a charm.
If you cannot connect to another computer in your network then follow the above procedure and you will be golden.