How to warn the technician before arrival about possible problems? (5581SL)

On Wednesday, we expect a technician to connect to the fiber optic network. I didn’t find a feedback form anywhere on the site in my personal account to write to a specialist. A few concerns that I would like to convey to the technician:
1. Mobile connection in the house is extremely poor. Therefore, there may be difficulties with a preliminary phone call. But I will definitely be at home.
2. T-Mobile, which I chose at the beginning, was not able to get the Internet into the house, referring to a problem with the fiber optic connection. It must be checked with special equipment. And also the specialist needs to have access to the switchboard outside the apartment, I think.
3. In the parcel from KPN, only a router came, but there was no converter for fiber optics itself. Will the technician have a converter with them? Is this common practice?

Can the forum service pass this data to the connection department? Yes, I know I'm naive, but still.