I need to connect a computer in another part of the house to a gateway/router in order to use the internet for online gaming. Motherboard has two gigabit ports. Hard wiring is not an option. Router has wireless G. Tried powerline adapter, linksys, with mixed success. Now it doesn't work anymore. Is there a better solution? Also gateway/router cannot be replaced as it's used for the TV and phone, AT&T U-Verse.
Powerline adapters can be a good solution if you buy good enough ones and the power circuit in your home was laid out appropriately.
I assume you've tried the above because wireless is out of range. You might add a second wireless router to extend the signal.
Usually you can only do this via an ethernet cable between the wireless routers but if both support WDS (and are preferably of the same brand) a wireless link between them will work.