My wallet syncs but never catches up, and always stays the same amount of time behind.
This issue occurs when the system clock is not properly synchronized.
For Windows 10: Click on Start, then type "time", and select "Change the date and time." Make sure "set time automatically" is checked.
For Windows 7: Double-click the clock in the lower right corner of the screen. Click "Change date and time settings". Click the "Internet Time" tab and make sure internet time is enabled.
For OSX: Click System Preferences, then Data and Time. Make sure "set date and time automatically" is checked. You will need to click the lock icon to make changes.