[masklinn]

Does your UPS have a plug for laser printers, or just for printers?

It might be assuming an inkjet, which have much lower power draws: an inkjet will draw maybe 50W. A laser printer are generally in the mid-hundreds at least and some models can get into the high hundreds to low kW, you need a pretty heavy UPS to handle that and still power other systems.

[Loic]

For laser printer, it is specified on the plug. It protects only against power surge coming from the utility provider. It does not provide power to the printer, this is just a protection if your house is hit by lightning.