Wireless Connection

I have a mostly wired network centred around a linksys router located in an upstairs bedroom. I occasionally work of a laptop located in a downstairs dining room and connecting via WiFi. The WiFi connection was being lost frequently, and using Inssider I found that there other WiFI networks using overlapping channels with a stronger signal. So a couple of questions, am I correct in assuming that it is these other, stronger networks that causes the loss in connection? If so what should I do about it?
I have a wired connection to the TV etc downstairs via a powerline adapter.
Any thoughts and suggestions welcomed.

Generally it is a case of switching around the channels to find one that works best, or adding a 5GHz wireless access point which has less congestion.