Hi everyone.
Hi again ploum
I tried to add the string suggested by davidfor, but it doesn't help to fix the issue.
I also have a router of telecom company with WPA encryption.
I tell you that i have not problems when i connect to the hotspot of my phone cell, or when i connect to routers of some of my friends, who have other kinds of router.
So i am wondering if the problem is related to telecom routers.
Yesterday, i saw that the official twitter account @KoboHelp answered someone that this is a known issue and they are trying to solve it.