If you bought the printer from a managed service provider (MSP) or a previous owner, they likely changed the default password to match their security policy. In this case, you will need to perform a factory reset.

If you need to change settings directly on the printer's touchscreen:


There are three common default username and password combinations used for the M3550idn. Try these in order:

Option A (Most Common for Newer Models):

Option B (Older Firmware):

Option C (Legacy/Basic Login):