Synology DSM: 2FA "Remember This Device" Not Working

13 November 2024

If DSM keeps asking for the 2FA code even though you tick Remember this device:

Control Panel > Security and untick Clear all saved user login sessions upon system restart.

Also check:

The browser keeps cookies for the NAS address (no private mode, no "delete cookies on close").
You always open DSM with the same hostname. A trusted device on nas.local is not trusted on the IP address.

More info.