Router set up log in problem

[#1]

I`m trying to set up my Thomson TG585 v7 router on a new pc and netbook and i think its all connected right  as all the lights are on but on both computers it puts me on to BT enterprise`s website broadband set up page asking me for a workplace username and password and to contact the corporate administrator if i don`t know what they are.
What on earth is this my broadband is already set up and has been working for years with a modem and my ISP isn`t BT its Plusnet but the line is BT`s. Workplace username what is this? I don`t work for BT. Do I have to phone  BT or Plusnet for the username and passwords?
Does broadband have to be set up again when you change from a modem to a router? Anyone else had this problem?

[#2]

Welcome to the forum DC676
Workplace is (or maybe was) the Plusnet internal system and it's highly unlikely you would be able to log into that.
Have you recently migrated from another ISP (BT maybe)?
Have you called Plusnet Support? (the number is on my sig below)

[#3]

I suspect you haven't entered your broadband username into the router properly. That needs to be accountname@plusdsl.net (assuming your account is a Plusnet one (rather than Force9, etc)).
accountname is the one you use to login to the Member Centre. Your password is the same one used for that Member Centre login.

[#4]

Quote from: Strat

Welcome to the forum DC676 Workplace is (or maybe was) the Plusnet internal system and it's highly unlikely you would be able to log into that. Have you recently migrated from another ISP (BT maybe)? Have you called Plusnet Support? (the number is on my sig below)

Thanks. No I haven`t migrated from BT only Madasafish which was last year.
No I haven`t called Plusnet support yet I was trying to avoid that if its an expensive 0845 number!

[#5]

Quote from: spraxyt

I suspect you haven't entered your broadband username into the router properly. That needs to be accountname@plusdsl.net (assuming your account is a Plusnet one (rather than Force9, etc)). accountname is the one you use to login to the Member Centre. Your password is the same one used for that Member Centre login.

Do I need to enter my plusnet username on BT`s page? BT`s broadband setup page  was the first page that came up on my desktop pc but on my netbook I started off on Thomsons page as in the router instructions but then step 6 with the Easy Setup Wizard wouldn`t appear and the BT page came up as well. 
I don`t understand why the BT page comes up or why I have to set up broadband when It`s already set up. 

[#6]

Routers (more correctly router-modems) work differently from basic modems. With a basic modem one PC connects to the ISP; with routers the router itself connects to the ISP through its internal modem, all computers (desktops, laptops, netbooks, smartphones, …) then connect to the router over an internal network which may be wired or wireless. Once connected to the router these computers are then implicitly connected to the internet, the router directs (or routes) transmitted data to and from the appropriate devices.
If your router is configured with easy start it should connect to Plusnet, configure itself and switch to your account automatically. That process takes about 15 minutes. Otherwise you have to connect one PC to it (preferably using an Ethernet cable), log into the router admin pages and use the simplified set up process if that comes up to complete configuration, or the set-up wizard as the final fall back.
I am assuming you have a Plusnet supplied TG585, at no time should you end up connected to a BT page. If you do something is wrong.
It's difficult sorting out from your description whether your router is connected to Plusnet or not. Obviously you managed to post here so you have connected by some means. If you are using the basic modem for that it is important to disconnect it from the line when trying to set up the router - two ADSL modems on the same line will not work. If the router is not connected to Plusnet I would be inclined to reset it to factory defaults (use a paper clip to press the sunken reset button on the back for 10 seconds) and start again.