SkyQ mini boxes always buffering

[djm123456]

Hi, 

I have a 3 story house with the the main SkyQ box on ground floor, mini box and sky router in seperate 1st floor bedrooms (phone connection comes into the house on 1st floor thus router here), and another mini box on the top floor.

On both mini boxes we get constant buffering whilst watching live or recorded tv... sometimes also have problems getting them to connect to main box at all.

I have rebooted the whole system multiple times over the last few weeks/months but the issue remains.  Is there some sort of signal booster that would help ?   or would powerline/homeplug help ?

thanks

Darren