have wireless network in my house. our desktop keeps losing its connection, while our laptops’ connection stays on. any ideas?

so yes I had decided recently to obtain my own Internet connector device, while there is already a modem. However I’ve been desperately trying to get two laptops of mine to connect to the internet while I’m using the internet connector device in one of them, I’ve reeked almost every where but no progress
thanks for reading.

I am never more than 10-20m away from the router and we have normal brick build construction, one hands free phone handset and a few mobiles. Both laptops have always had excellent signal strength but now the SOny Vaio has suddenly dropped the connection unless I sit alongside the router. What can I do to remedy this?