connecting via 3rd party router (linksys wrt54gl)

[#1]

hello. i am a new customer to plusnet. moved here from virgin because of change of location and not much available in the area.
currently got 9mb/s down and 0.5mb up on a line. not expecting super speeds or anything but when there is 2 devices connected to the internet one completely stops.
eg if i connect iphone and download app updates or anything like that the main PC can barely load a web page. As i said not expecting much because it is slow line, but your router Plusnet2704n
doesn't offer any qos or any type of speed management or at least i cant find any when i log in to the router.
So question is is this linksys wrt54gl is compatible to use with plusnet broadband and how do i set it up?
I followed some guide i found on your website to set it up
http://imgur.com/ZcwORpc

But keep getting error like this
http://imgur.com/72ovcu6

So any help how to configure this linksys router or any advice how can i manage traffic with plusnet router would be appreciated. thank you

[#2]

Hi and welcome to the forum
The WRT54GL can be used with FTTC broadband but not directly with ADSL as it does not have a built in modem.
If you're using it in conjunction with your 2704 router then this will be authenticating your connection and you'll need to set the Linksys WAN port to DHCP rather than PPPoE.  Using two routers in this way is not generally recommended however so you maybe better off looking for a different router, or something like the Draytek Vigor 120 ADSL modem to use between your line and the Linksys.

[#3]

I see i thought those days are over where you need modem and router. Really thought most modern routers would had modem built in it.
So if i connect plusnet router first, when the linksys router to it and then my PC when it should work? And how about qos, will i be able to manage traffic properly that way?