Thank you LDLC
In the end I didn't do business with Aquilenet
(I couldn't "talk" to the modem-router from my PC)
I use a "La Poste, SFR" box that uses 4G
In addition, I stopped using my smartphone and switched to a simple Nokia Tel from "La Poste Mobile".
Thank you for this experience with you (at my age there won't be many left).
Bernard PROUDHOM