Change your router password. Even if your ISP haven't given it to you.

We changed ISP and got one of their preconfigured router because it was cheap for the hardware and that way they can't just put any issues down to non-standard hardware.

ANYWAY.

They shipped new router, and it had a default account and made you change the password on first login - which is good - but it's not actually the admin login, which they (a) haven't actually provided and (b) have left as the default admin credentials you can find in less than a second by googling the make and model.

I mean, I know to go look for this stuff - how many of their customers are just changing the password for the account they've been given and assuming it's fine!