cant log in to tg582n router

[#1]

I understand that to log in to your router admin is the username and the routers serial number is the password However despite putting these in (using proper case etc) my router states one is incorrect ! ? Any ideas please?

[#2]

It all depends on the router.
Some routers are setup to use 'admin' and 'password' when they arrive.
You change the user and password before you use them.
I expect Plusnet have setup your router for you, in the belief that this is helpful.

[#3]

thanks I will call the number