(Disclaimer: I am not nor have I ever claimed to be a networking guru of any sort! I just speak from my own personal experience and knowledge. Actual terminology/definitions may differ. I am a broadband communications technician, plain and simple, but have boldly ventured into these areas on my own accord, mostly out of curiosity!) If I understand you correctly, you want to use the wireless router as a wireless bridge? If so, you would need to install DD-WRT, which is basically installing new firmware into the router. Unless, of course, the router already has bridging capabilities. (there are, I believe, at least two different kinds of bridging, they just go in opposite directions, very important! One bridges through your modem, the other bridges wireless to Ethernet, basically running in reverse, so don't just buy a router simply because it has "bridged" mode) An easier way to go would be to simply buy a wireless bridge, or use a power line Ethernet adaptor. Or, better yet, run a Cat 5 or 6 and use a $10 (US) switch.
A link to wireless bridges at Newegg: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=wireless+bridge&N=-1&isNodeId=1
That Linksys WUMC710 Wi-Fi Wireless AC1300 5GHz looks like a pretty good deal! We use the same kind as an access point ( a one-port version with the Cisco label) at work to stream hi def video (3 streams simultaneously, people have done up to 6 successfully with no hiccups) and it works fantastic. Only 3 stars rating there so results may differ! Be sure your wifi access point supports 5Ghz though, LOL, good luck!
Sorry, I've edited this so much I forgot most of what I was thinking, LOL! I was just looking at that Edimax bridge for $29.99 and it looks an even better deal. Not familiar with the brand, but it got 4 stars!
Another edit: I just realized that they may have different offerings in Australia, even though I believe the standards are global (they are, I looked). So I looked, Oh, my God! HUGE difference! I don't even know what to advise you on. Looking at the choices, I think the HAWKING HWABN1 Hi-Gain Wireless-300N Access Point/Bridge would do the trick. AUD$129.70. I have no idea how much that is in comparison! Sorry!
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