I bought one of these for my dads house, you just plug it into a wall socket at a suitable point. You then connect up to it via wifi set the wifi password and ssid of the wifi you want to boost, job done. No need to touch the original one.
I set it up with a mobile phone, didn't even need to use a computer.
He should first check if he is able to boost the signal strength by going into the settings for the router. Mine gives me a drop-down list with values from 25 mW to 400 mW. It was set to the highest by default, so if that is the norm, then that will not do much good.
Altering the length of the antenna will not necessarily work. The antenna used on both sending and receiving devices is "tuned" to the frequency of the carrier signal (details: it should be either one quarter wavelength or 3/4 wavelength at the speed of light).
My recommendation is to somehow move the devices closer together or buy a repeater or second hot spot. I am about to do this myself and haven't figured out why there is a vast range of price for similar boxes. I am looking for one that has several cat 5 ports at 10/100/1000 and firewall and hot spot. The price range is $39 through $200+ for similar functionality as described on the packaging.
A number of inexpensive wireless routers can be configured for repeater duty. I'd recommend that course first, as few devices these days offer an external antenna connector. While you might not be able to be there with him, I'm sure you can download a pdf of the manual and walk him through the configuration over the phone.
Like others have suggested the antenna should work, but also check the location of the router. It should be away from cordless phone / microwave oven. also try changing the wifi channel on the router, sometimes it has interference from neighbours wifi / your own cordless phone. Also it should be higher from the floor and away from the wall.
Normally, antennae are tuned to the frequency of the signal they produce, fitting a different sized one is likely to drop the signal strength. If you have a spare or cheap wireless router you can turn it into a repeater. The router might support this out the box, if it doesn't you can upgrade the firmware. This article[^] gives an overview of doing this (with one of the WRT variants in the article, you could also consider Tomato[^])
The other thing I have heard (but don't know if it is true) is that the firmware on the router restricts the output power. There may be an option to boost the power, or possibly your could replace the firmware with the above. If you do decide to flash a router, make sure you check the compatibility list for the firmware you are using. Also flashing like this will invalidate the warranty, in case your friend worries about such things.
Well, I was working on an XML document in VS2012, and created a schema for it. VS then gave me the error "Schemas property will be ignored because the document does not declare any matching target namespaces", even though I did not declare a target namespace in the schema file. I did so, and put it in the XML file's 'xmlns' attribute, but VS still showed the error. Closing and reopening the file didn't work, but restarting VS did.
I think that is a bug. (Or is it an unplanned feature?)
Sounds similar to the unfortunate times I have used Eclipse, with it highlighting syntax errors that either simply do not exist, or still showing the highlighting even though the error has been corrected.