I'll be very pleased if this solves some problems.
The neighbour's signal is always coming in stronger, so I doubt they even noticed anything. It's not like I shouldn't have checked when I set the router up, but I'm not very familiar with routers and when I received it from the ISP, they said it was all configured and good to go. If you hadn't suggested it I may never have gone into the router, known what to look for and fished around in the settings. So, thanks for that.
You think that's all it was? Just two routers on the same channel?
I've found some of the settings in the router but I don't know where to look at my network card settings to compare them. Maybe this isn't necessary now?