I had a wired connection to my router until recently, and I would always get around 750kb/s.

I've recently switched to wifi as I've had to move the router to somewhere else in my house. I've noticed that the signal really deteriorates when we have low pressure weather, i.e. it's overcast, cloudy or rainy.

Yesterday we had rain all day and my signal dropped to the 5.5MBps band so I was only getting speeds of around 20-100kb/s. This morning, it's beautifully sunny, not a cloud in the sky, and I'm on 36Mbps with a download speed of 850kb/s!

I don't think it's contention at the exchange or network shaping since I get 750kb/s constantly, no matter the time or day, on a wired connection.

Although, saying that, my speeds over the last few hours has been a constant 850kb/s and I didn't even get that when wired, and my exchange is currently going through (or is imminently scheduled for) the 21CN upgrade. Maybe that has conincided with me moving my router, although I moved the router 1 month ago and I don't think the upgrade would have taken that long?