There are several free and paid apps to do wireless analysis.. I suggest you use one of them on your ipad.. I don't use them so unsure what to recommend.
On the PC there are lots of great softwares .. inssider is popular one.
In the setup of the Extreme which I hope you did from the ipad..
You should NOT use apple names recommended by the setup wizard.
Change names to short .. 2-20 characters, no spaces and pure alphanumerics.
All passwords should be same, except you can have 8-20 characters.. more only needed to calm your paranoia.
Setup fixed channels.. and different wireless names for the two bands.
Since 2.4ghz is flooded.. try and use 5ghz as much as possible.
The apple wireless setup often has issues with PC wireless cards.. Intel in particular.. ie most laptops. Do not be at all surprised to get issues with windows.. and latest iOS is hardly any better.
But the setup of the Extreme.. after you have done the above.. is subject to sudden wireless dropouts.. if it continues.. take your AE back to apple for testing/replacement.. although half the time the replacement is no better.
Post screenshots from the ipad of the setup if you want more details.
And I need to know what broadband modem you have and how the AE is setup.. bridge or router to start with.
