All devices not able to access Wi-Fi at work?

My workplace has Wi-Fi sourced from my boss s parents house. It was supposed to be extremely effective and could be used out of range and all over the yard etc (they paid a lot for it) but it doesn't… I live on site and the Wi-Fi was working brilliantly for the few weeks it has been up, but since Tuesday it has been wavering. It will work on my phone for about 20 mins at a time once a day then give up. It works on my ipod for an hour or two but then gives up around night time, works on my laptop the best but has to be turned on and off again and again until you can get a decent connection. I wish I could say it was weather/problems with source/someone messing with it, but it works fine for everyone else and the only place it works fine for me is the bottom yard.
It was working great until then. Is it an issue with my things or…
There's no point in me saying anything to my boss as she is unlikely (and I don't expect her to) spend any more money on it and it won't get fixed anyway. It's just irritating as I live away from home and am currently doing bookings etc for Christmas. Any ideas/help/info?
(My iphone/ipod/laptop won't even display Wi-Fi network when I go to settings, it will just disappear).

"It was supposed to be extremely effective and could be used out of range". It might be extremely effective, but there's NO WAY it can be used out of range.

There's no way that it can be showing problems just for your three devices but nobody else is having any issues unless they are in a different part of the network's coverage from where you use your devices.

Unfortunately, statements such as "it works fine for everyone else and the only place it works fine for me is the bottom yard" is fairly meaningless without knowing the layout of the buildings, the yard and the Wi-Fi source.

My suspicion is that there's another Wi-Fi network that is causing interference with the one you are using. This might be a new network that has appeared on the same of an adjacent wireless channel. As many home type routers are configured to choose their wireless channel automatically, if either your employer's router or a nearby router has rebooted, then it could have picked a different channel from the one it used previously. My son used to live in an apartment in a large multi-floored block. His router was in one room and his home office was at the other side of the apartment. He had very unreliable Wi-Fi. I did a survey and found that at the router, the channel that the router had automatically selected was by far the best channel - free from any strong interference. At the other side of the building there were several other networks on the same channel that were just as strong as his own router. At least one of these other networks was not even detectable where his router was located. He tried several different channels and eventually fixed his router on the channel that gave him the best results.

If you live on site, it might be worth buying your own router for your accommodation and installing an Ethernet cable back to the bosses network. Ethernet can run to 100 metres, which is typically further than Wi-Fi will work, especially through brick walls. You would have to discuss this with your boss, but if she is willing to let you do it it could cost you less than $100 to implement yourself. It might not give you access over the whole site, but it should allow you to get good connections in your accommodation. If your work requires you to have Wi-Fi coverage over the whole yard, then it is really your bosses responsibility to provide that coverage. Leisure time coverage should really be up to you unless it is part of your contract.