I wonder if maybe the fan is being controlled by another remote with the same dip switch set up. Do you live in an apartment building, or in a place where it’s possible that another ceiling fan is installed and the remote is controlling more then one fan by accident?
If you’re not sure what we’re talking about, check out this article that helps to understand how ceiling fan remotes are programmed by dip switches. You could try changing the dip switch setting if you believe that the fan is being controlled by another remote by accident