My guest decided in the middle of her stay that she doesn't want to stay anymore because the wi-fi signal was too slow. She said that everything is great but the wi-fi. I had problems with the wi-fi this week but it is still working, not just super fast. I offered her a portable wi-fi while the house wi-fi is not perfect and she refused saying that now she is too sad and want to leave the place. Do I have to accept this reason to cancel her stay in the middle of the reservation?
A guest can cancel for whatever reason or for no reason at all, but they must acknowledge that the refund will be according to your cancellation policy.
If you offered an acceptable replacement for the temporary wifi-trouble, there should not be a reason to leave in the first place.