First of all, I don't have a quick and easy answer to your problem with Linux. Instead, I'll just focus on a simple, reasonable hardware solution to the problem.
As for the Linux issue. You could check with some of the many Linux forums and chat rooms available. Sometimes you will come across somebody that had the exact same problem and found the solution.
Now about the hardware. Presently there are on the market a number of remote control switches that work over the Internet. In this case I'm not talking about switchers, but actually literal light switches. In fact some of them install in a light switch boxes. But can also get a light switch power plug that were works over wireless.
Basically here's how they work. Your wireless router has to be open an online at all times and be able to do the proper port forwarding to allow remote control over wireless. Sometimes this feature is blocked, but apparently it's not hard to do. Otherwise, these companies wouldn't be selling these things ever was too hard to do. Expect to pay about $30 for one of these little gadgets and it should handle about 300 to 500 W of power. If that is an issue, there's a workaround around that also. Need to check the power rating.
Once you get one of these devices you can play around with it and see how it works you send a signal over the Internet and it comes back to your wireless router and the wireless router relays it to the light switch controller. If you get the controller that has a plug, then you could just plug in a PC to the plug. But for testing purposes, you would start out with just a lamp see how the thing works.
Now if there is a power limit issue, a little more hardware is required. Instead of switching the power supply on an off for the computer, you devise some method where the light switch controller could activate the power button in some fashion I'm sure others have done this, but I have not done it myself. Also, it may be possible to find controllers that have better power ratings. You probably want a controller that would take up to 800 W to handle your gaming server. By the way, how much power do you need to turn the thing on from a cold start?. Also, do you have your server set up to worry it will start up on cold start? This means you have to have some type of auto login script or a some other means to get around the password requirement for sign in. Once the computer is powered up, the script would start that monitors your network for an incoming request.
Does that sound feasible to you?
* In the USA a plug must allow current up to 15 amps to comply with safety standards. But the cheap comptrollers come from China. I am not certain if they are rated for that much current. On eBay about $30. Some a lot more.
Photo from eBay
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