Purchased an upgrade - immediately lost internet!

[#1]

I've just upgraded my package to unlimited fibre extra via the website. The new package will start on 14th Oct (6 days' time).

My existing Plusnet broadband stopped working just after I got the email confirmation of the upgrade.

If I try to access any website I get the message "Your Internet authentication failed. Before you can authenticate yourself, you have to login as a more privileged user."

If I log into the router (Thomson Gateway) and run a connectivity check I get "No ATM activity detected on your DSL line" and "PPP Authentication failed".

I've tried restarting the router.

Edit: When connected to the router, if I check Connection Information under Internet, I see the credentials that Plusnet gave me when I first got my broadband, along with "Last Error Message: Authentication failed". I don't have any new credentials, as I only just selected the upgrade on the website.

[#2]

Fixed it!

Before I could log into my account to pick the upgrade, I had to reset my password.

I didn't realise the router uses the same password to connect to the internet. Of course I didn't read the password rest emails that were trying to tell me that.

I have an old router and I had to update it manually.