Please note that before completing the steps below it is recommended to backup the 'shared.storage' before making any changes.
1. Open shared.storage file in a notepad
2. Search for:
3. Make sure domain id value in the next line corresponds to your domain
4. If it is not your domain search further until you see your domain
5. Find "<forcedDCs>" section below and make sure it looks like this:
<forcedDC type="Request" />
<forcedDC type="Default" />
6. Save the file
7. Open Admin site -> General settings -> Save
8. Open Admin site -> General settings -> Domain connections -> select your domain and specify the required DCs.
(it is also possible to simply change old DC in shared storage on step 5.)
Reminder: You may want to backup shared.storage before making changes.