WLI-TX4-AG300N Ethernet Converter - Problem connecting to the internet.

[StuartG48]

WLI-TX4-AG300N Ethernet Converter

I've recently moved my PC into a home office in the garden and my son gave me his unwanted ethernet converter to connect the PC (Windows 7 Home Premium) via wifi to my BT HomeHub 3 network. The PC has no built in wifi and was previously connected directly to the HH3 via ethernet cable. The setup CD is missing and I tried to set it up using the browser interface. I could log on ok and was connected to the wi-fi network but I couldn't get an internet connection. I kept getting a message that "The target ethernet converter couldn't be found."

My son thought the problem might be legacy setting from when he had it. He came over and set it up for me also through the browser interface. He got it working ok except I got messages from my computer on startup that there was an IP address conflict, "another device on the network has the same IP address as this computer" - something like that. Didn't seem to affect performance and I could log on to the internet via the ethernet converter no problem.

Redecoration meant I needed to move the phone point and the HH3 to another phone point further away from the garden office - too far for the wi-fi signal to reach. I bought a Netgear WN3000RP-200UKS wi-fi range extender and set it up where the HH3 router used to be. I used the WPS/AOSS switches on the wifi extender and the ethernet converter to connect them but the blue security light on the ethernet converter just flashed continuously and there was no connection.

I used the Ethernet Converter Manager to reconfigure the new connection and although it could "see" the extended network and Windows network manager showed me as logged on to the wi-fi network via the extender but there was no internet access.

Windows networking troubleshooter took me through re-booting the ethernet converter and re-setting IP addresses then gave up suggesting I seek further help on the web.

I brought the ethernet converter back into the house close to the HH3 router, reset it to factory settings and connected it directly to my MacBook via ethernet cable and reconfigured it for the HH3 router. Then I re-configured it again for the Netgear extender. That seemed to work ok but when I took it back in the office and connected it to the Windows PC it again said it could see the Netgear extender and was connected to the home network but still said I didn't have internet access. I've reset IP addresses back and forth between manual 1.1.1.1 for ethernet converter and 1.1.1.2 for PC but Windows troubleshooter said I needed a DHCP assigned address.

I've logged on to the ethernet converter browser interface from the PC and reconfigured everything to use DHCP and now I'm getting "Target Ethernet Extender cannot be found" again.

Clearly I'm missing something, any help would be appreciated.

My setup is:
BT HomeHub 3 ADSL router with built in wifi
Netgear WN3000RP-200UKS wifi extender
Buffalo WLI-TX4-AG300N Ethernet Converter
Home assembled PC running Windows 7 Premium (no built in wifi)

I also have a MacBook pro but that has built in wifi so I don't need to use it with the ethernet converter. the MacBook picked up the Netgear extender from the garden office and connects to the internet with no problem.