Heat affecting Broadband?

[Deborah5]

I moved into a new home 4 months ago. It's a dormer bungalow & router is located in one of the attic bedrooms (that's where previous owner had it). I ventilate the room as much as possible but with the heat this summer, by 6pm I find my Roku keeps buffering. Every night I'm having to go through the rigmarole of turning router off, waiting, putting back on etc. Anyone have any ideas? 

[WSH]

There is usually no easy answer to this, but as no one else has picked it up, I'll see if I can help. 

Firstly, are you sure it is down to the router and not something outside your home?  For example, are the neighbours having similar problems?

Is this a Full Fibre (FTTP) connection or a Part Fibre (FTTC) connection?

What make is the router and how old is it?

I take it that it is not sitting in direct sunlight?