You exceeded the run of the mill and I want to state this is fairly advanced since the internet is not from a classic source. That is, you must be very well versed in networking to set it up. Even if I did this for you, you would need ongoing support which I can't sign up for since this is free and volunteer.
I suggest you get a classic internet source even if it is the lowest speed DSL.
A while back I bought a HP ProLiant N54L on a cashback offer instead of bothering with a NAS which was the same price. Now, I know nothing about networking - but somehow - I managed to set it up with a copy of Windows Server 2012 R2, connect it to a cheap £12 unmanaged network switch and quite happily watch movies and zap about files via Ethernet between my laptop and desktop. After using the 'Connector Wizard' it seems to work flawlessly.
Now, I want to try and add wireless functionality to my home network so I don't have to bother with an Ethernet cable on the laptop (but also stream music to phones) - and I have a TP Link TD-W8960N which I'm hoping might do this job. Thing is, I've tried plugging it into the switch and fiddling (even though I don't know what the hell I'm doing) and generally I just seem to break the working link between my N54L and Ethernet computers until it's removed from the switch.
It's important to note we don't have internet (except tethered 3G -- though from what I gather I can't bridge the router to this, can I?). The unmanaged switch also shows up as a "unidentified network"/DOMAIN.local on the server/laptop/desktop - anyway sort that?
So yeah, can I theoretically use the wireless router to extend the network? But perhaps also provide internet via the 3G phone that we use? How might I go about doing this?