The WIFI is now working pefectly. I changed the loose cable and there is no connexion problem anymore. I Could not help Tommy the way I would have wanted to as he checked in on a sunday and my internet provider was out of reach. Fortunately the WIFI was back on the next morning.
Also, I always make myself available to help my guests find my flat. But unfortunately that day Tommy showed up 1 and 1/2 hour before the check in time so I could not be as available as usual.
For the rest I'm really sorry that my flat did not meet Tommy expectations as I really try my best for my guests to have a great stay at my place.