AirPort Express (2nd) Internet Connection Speed

Question

Dear All
First of all, I looked everywhere on the internet about this issue I’m having and couldn’t find any solution. To explain my issue let me tell you how and why I use AirPort Express shortly;
My Purpose
I have a wireless network and all my PCs are connected in one network. I have a Windows server and using it for general purposes and also as a file server. But if someone joins my network, they all are able to see my shared folders. They are able to read/write files (even delete them).
So I decided to create 2 networks with AirPort Express (2nd Generation). I have a wireless network for internal use only (for me and my PCs) and one Guest network.
Everything seems okay and there is nothing wrong.
How I Installed AirPort Express (APE)
I connected APE to my router (standard US Robotics DSL router) and my switch to APE. I used AirPort Utility on a Windows 8 PC and configured APE settings.
Base Station status seems normal (have a green light as well) and works okay. I can use my internal network, my PCs are communication with each other (they are all on the same switch). Guest network also works okay and seems like there is nothing wrong.
My router uses 192.168.2.xx IP range and APE is using its own 10.0.1.xx IP range. This makes APE to add an issue to Issues list as Double NAT.
What is Wrong?
I have internet connection and I can browse web pages and do that kind of things. But my internet connection is really slow and some times cannot display web pages. I have to refresh some pages a few times to display it. My ping increased 5-6 times over than normal.
I thought the problem is the PC that I’m using but then realized that every PC has the same issue. I made a speed test and it showed 352ms ping to the nearest server to me which is really a high value.
My connection is unstable. It’s not dropping but speed suffers. Here is a test result. In this test my ping was 31 ms but as you see speeds are suffering. My connection is supposed to be 8mbps (Down) and 1mbps (Up).
What should I do to fix it? What is the point I’m missing? Could you please help me? Please let me know if you require further information.
Thank you very much.
Best Regards

Answer 1

Dear All;
I just disabled DHCP Server from my router and now it seems to be better. But I don't know if it's something that I shouldn't do or not. Have any ideas?
This is the new result after disabling DHCP from my US Robotics router. There are still some minor issues (latency, slow downs etc.) but now seems to be better than before.
PS: I still have that "Double NAT" notification under Issues section.
Message was edited by: SakirSaka