It seems to be a common problem that one cannot access the dashboard of the new sites after setting up a WordPress multisite network. My Googling showed at least 8 different problems and solutions. Here is what I met and my fix:
1) After you setup the standard multisite network, you should be able to create site1.main.com and site2.main.com, and be able to access their dashboard.
2) You can then setup the WordPress MU Domain Mapping plugin. This will enable you to map site2.main.com to site2.com. (You need to own site2.com and be able to setup the DNS record and/or virtual host mapping.) Here comes the problem I met: my site2.com is working correctly, but I can’t access the dashboard of the site2.com anymore. It enters a login-loop and never goes anywhere. The URL looks something like this :
3) You can do two things here:
- Disable the Domain Mapping on network level. Go to dashboard of site2.main.com (change it back if you already set it tosite2.com). Enable the Domain mapping plugin on this site rather than on the network. Then in the “site admin dashboard->tools->Domain Mapping” set the site2.com there (Fig. 1). You will have a site2.com WP site, and a site2.main.com/wp-admin backend.
- Enable the Domain Mapping on network level. Besides all the official plugin setup instructions, you also need to add your site2.com in the “super admin->settings->domains” (Fig. 2). You will have a site2.com WP site and a site2.com/wp-admin backend.
I hope this will save somebody some time.