Ipod Touch/ Iphone can't connect to Wi-Fi but computer can

Just starting yesterday my Ipod has been unable to connect to my Wi-Fi connection in my home. It has worked fine before. We just upgraded and changed companies for our internet a couple weeks ago, but have never had problems until now. It was connected, but now it just disconnects and doesn't allow me to log back into it. It just says "unable to join the network '___'" I have tried putting everything in manually but that doesn't work either. It worked once, but then it disconnected again sometime while I was sleeping. What's weird was my little brother's Ipod was doing the same thing at the same time. I was able to fix it but I'm not sure if it's working right now. And what's even more weird is that my computer has no issues with the internet and is working fine at the moment whilst my ipod isn't. Help would be greatly appreciated.

Added (1). Okay well I have got it to work again for now after pressing the join button like 20 times.

It is something to do with apple. I had same problem long time ago. My ipodtouch couldn't connect to any network. There are 2 ways to fix it. If you purchased your product under 1 year, apple will give you full compensation which means they will give you new one. If not, you will pay as low as 10-70 dollars depends on the model.

On the other hand, you can completely turn off your device for 3 or 4 weeks without turning on. Leave it like that and after that just turn it on. It will work. I fixed mine like that.

Good luck.

By the way you do not need receipt to show them, apple will check by you device by its serial number.