Why does Nikon d5500 blur when shooting in night view mode?

The hand is shaking too much, or VR is not turned on.

The high-level ISO automatic switching function is not turned on, or the high-level ISO setting is too low.

Aperture setting is too small (aperture value is too large)

The focus assist light is not turned on, or the contrast at the focus is too low.

There is something wrong with the focus setting.

Suggestion:

To come up with a good film at night, it is recommended to use a tripod and focus manually with an LED screen.

If you don't have a tripod, remember to turn on VR, ISO should not be too low, aperture should be adjusted to the maximum (minimum), and multi-point autofocus should be performed.