Provided are an authentication method and apparatus, a device, and a storage medium. The method includes, if an optical line terminal operates in at least two bands, setting at least one low-delay band and at least one non-low-delay band; after receiving, in a non-low-delay band, a first serial number sent by an optical network unit (ONU) or an auxiliary authentication device, acquiring an equalization delay; after receiving, in the non-low-delay band, an authentication request sent by the ONU or the auxiliary authentication device, determining an ONU identifier according to the first serial number or a second serial number of the ONU in a low-delay band, where the second serial number is sent by the ONU in the non-low-delay band; and authenticating the ONU according to the ONU identifier and the equalization delay.