Hi everyone! This is my first post here in Geekzone so I hope I can articulate what it is I need some help with!

I recently purchased a Mac Mini to run as a server for a future new business and also to learn about Macs and running a server in general. I also purchased a Airport Time Capsule from a convenience point of view as the sever app automatically configures port settings in the router as I intend to run VPN and other services from the server. 

I connected all the new devices up and then began a learning curve into routers, modems etc!!!

I needed to configure the linksys to be just a modem and not a router, then set up the ATC (Airport Time Machine) as the router.

After some time studying the Linksys setup I decided that I needed to change the DHCP settings to disabled, and also tried the setting on DHCP relay.
Neither worked and after some more research I discovered that the Linksys on my ADSL+ connection is set to PPPoA when the ATC needs PPPoE. 

Please tell me I am right or is it still possible to use the Linksys WAG120N???

I can see a solution in using a Dray Tek Vigor120 as it has a PPPoA to PPPoE bridge. 

Other options are to upgrade to a VDSL connection if I have to buy another modem, fibre would be preferred but the fibre cable stopped 3 houses down the street!!! 

Buying a modem that can also be used with fibre would be a good idea, but the options I see out there include routers and WiFi, something I do not need to replicate.
I have had a look at Fritzbox and Zyxel VMG8324 but unsure if they are able to allow the ATC to be the router. 

Just in case this is needed, we have a Mac mini, 2 soon to be 3 PC's, Xbox and TV on the network, plus 3 laptops, ipads, and phones using the wifi. 

Any suggestions would be welcome and thanks for considering answering my questions.