Routers repeatedly forgot settings

We have a couple of the GL-iNet routers that we intended to use for internet backup services, and I noticed a problem with one that we set up.

Every so often the router forgets its settings, and someone on site has to log in, set up a new administrator password, and reconnect the 4G modem and WAN connections.
This has happened no less than four times, with three different units, and two different models.

Is this a common problem?

I want to know if you installed some packages and the flash is full?

If that is the case, do a reset in the UI and start over will fix that.

Could it be power failure? A faulty adapter or the likes? Did it update?