Sorry AlexPlease: don't mix topics. And, in clusion, as it was clear, this is a router-related issue. The most reliable connection, apart from LAN cables, of course, is a powerline one. The lesser wifi, the better.
Thank you so much for your help!You need to set a password, in your receiver.
Go into your receivers menu, network and click on password. Set a password, which can be anything, ensure you save this, on exiting, and then you can use this password for programs like Filezilla, dreamboxedit, etc..