Admin Login Redirect Loop

Recently my team built a wordpress site in a subdirectory of a main site (oitdev.med.jhmi.edu/ieedev/).
After building we decided to give the site its own domain to accommodate Shibboleth security (ieedev.med.jhmi.edu) with the files still sitting in the subdirectory.
The change went well for the front end, all pages/information showing.
The site is on an IIS server, so no htaccess file.

The problem is when logging in via wp-admin, after entering the admin credentials, the site loops from the new site to the old site and back, continuously until it errors out.

I’ve searched for solutions and attempted a few such as disabling all plugins and clearing browser cache, but no luck. Then I added ” define(‘ADMIN_COOKIE_PATH’, ‘/’); ” to the wp-config file and that helped somewhat – during the redirect loop, hitting a refresh (F5) would take me to the dashboard of the site.

While that allows access to the dashboard, its still a problem, so I’m trying to figure out where that redirect loop is coming from.

Any help is appreciated.

Thanks,
FH