How to prevent buffering and possible slow network please.

Hi,

I'm new to the forum but hope to seek some guidance on how to improve my current setup.

Currently I have:

Ground Floor

Router - SR101

-> Homeplug Netgear 4 port 200mb to SR101
-> Homeplug - TP Link AV 500 to SR101
-> TP Link Gigabit Switch (1) connected directly to SR101

-> Sky HD Box to Gigabit Switch (1)
-> Synology DS214 to Gigabit Switch (1)
-> WD TV Live to Gigabit Switch (1)

-> Sony TV to Netgear 4 port Homeplug
-> WD TV Live to Netgear 4 port Homeplug
-> Wii to Netgear 4 Port Homplug

First Floor

-> TP Link Gigabit Switch (2) to Homeplug TP Link AV 500

-> WD TV Live to TP Link Gigabit Switch (2)
-> Humax Sat Box TP Link Gigabit Switch (2)

As much as not everything is ever in use at the same time and rarely in multiples of more than 1, I'm finding the speed of connections to the first floor are poor with lots of buffering even with just 1 in use e.g BBC iplayer on Sat Box or WD TV Live.

Any suggestions would be hugely appreciated.

Thanks in advance

Anil