Hardware tokens may occasionally become out of sync with Duo's service. When this happens, passcodes generated by the token fail to authenticate the user. You can manually resynchronize HOTP hardware tokens purchased from Duo or third-party vendors from the Admin Panel. TOTP tokens imported into Duo cannot be resynchronized.
To resynchronize a HOTP hardware token:
Log in to the Duo Admin Panel, click 2FA Devices in the left sidebar, and then click Hardware Tokens.
Click on the Serial Number of a token to access the token's properties page. Once on the token's properties page, click the Resync Token button near the top of the token's properties page.
Enter the code displayed on the token as the 1st code. Advance to the next token code and enter that number as the 2nd code. Advance to the next token code one more time and enter that number as the 3rd code. Click the Resync Hardware Token button after entering all three token codes.