If it can't detect the network automatically, but sometimes connects if you manually enter SSID etc, then it does seem that it's at the limit of it's connectivity. This is probably down to a) the LG's antenna being in one of the worst places possible in a cabinet with lots of other wires etc around it, and b) the adapter in the LG being low power.
Your laptop probably has a much higher power client adapter and also is not encased by a cabinet with other electrical equipment.
You might want to look at:
Linksys by Cisco Wireless-N Access Point with Dual-Band WAP610N
or
http://www.linksysbycisco.com/US/en/products/WET610N
It may have a much stronger pickup and therefore work inside the cabinet, or you may be able to position it outside and run a cable in. It should extend hopefully your existing network, but I would double check with Linksys. You may also be able to attach it to a switch inside your cabinet and use it to drive multiple devices, although I wouldn't expect multiple devices streaming at the same time...
This is one of the reasons I'm not so keen on WiFi on all devices as it'll be rather disappointing for many people, and a pig to troubleshoot. Especially if there are lots of other wireless networks nearby.
Also worth checking is the wireless channel. It should be either 1, 6, or 11 by preference. If you have neighbours with wireless, use your laptop to see what channel they're using and pick one of the above that's furthest away from the one they have. So if the strongest nearby network is channel 1, pick 11.