So I tried everything in this post for the app store, and nothing. Then I tried pokenguen advice:
https://osxlatitude.com/index.php?/topic/6559-app-store/?hl=%2Bopen+%2Bdpcimanager+%2B1.5&do=findComment&comment=38625
- Go to /Library/Preferences/SystemConfiguration/ and delete these files:
CaptiveNetworkSupport
com.apple.airport.preferences.plist
com.apple.network.eapolclient.configuration.plist
NetworkInterfaces.plist
- Go to System Preferences > Network, delete all connection. Then restart- Go to System Preferences > Network, add your connection again.</p>
This fixed it for me.
Just an FYI using the fix for imessage also was part of the app store fix. I couldn't get it working with one without the other