Fixing considerable lag on PS4 - need networking help!

Hey guys,

Thanks in advance to anyone who can help shed some light to see if I'm doing the right thing to port-forward my PS4 and get the best results for gaming. Apologies if this is in the wrong section or inappropriate.

To begin, here is a basic diagram of my home network (apologies if it is hard to understand, its my first time!)

http://i57.tinypic.com/11j9bew.png

Can also be viewed here.

Dotted lines are wireless connections, whereas solid lines are wired.

This network was done many years ago by an IT company, however in the last few months I've added the Belkin Range Extender to my Level 3 bedroom as I've now got a PS4 in there.

So now to explain my problems:

- I've got considerable lag and poor download speeds on my PS4.
- In an attempt to alleviate any issues, I'm trying to port-forward to the PS4 (ports 80, 443, 1935, 3478-3480).
- I've set a static IP for the PS4 (192.168.1.111) which works fine, and have set the ports to forward to that particular IP.
- I originally only forwarded ports on my Linksys Router, but have now also done so on my Netgear Gateway. I am unable to do so on my Netgear Router (on Level 2) as it apparently only working as a wireless access point.

Questions I have for you guys:

1. How do I check if my port-forwarding is working? I honestly haven't seen any real increase (besides a small jump in download speed - not latency/lag).
2. What are some changes I can make to the network to make it work better? Besides a direct wired connection to the PS4 (we don't have wired access points on Level 3), what are some things I can try? What are some other settings I should try (QoS, etc.)?

I understand that my PS4 (on Level 3), wired to a range extender, which is wireless to a wireless access point directly below (Level 2), which is then wired to my router on Level 1 is by no means a clean connection, but one which hasn't impacted me particularly with downloads, videos, Netflix etc. on my PC (and Netflix on PS4). I also understand that connecting to US game servers from Australia also presents a significant obstacle.

Again thank you all in advance for any discussion/help you can provide.