Many years ago a friend had ADSL broadband installed. The ISP supplied router wasn't very reliable - but couldn't be replaced because the unique user's broadband login password in the config wasn't known. The help desk had no idea what it might be - "it should just work".
A browser "view source" of the config page for broadband showed the password field as clear text. A decent ADSL router was then installed and ran for years without problems.
Recently the friend upgraded to 35mbps. The ISP supplied a new router - and wanted their old one back in exchange. Luckily*** it was still in its box in a cupboard - in apparently pristine condition.
***The friend is a "tidy" person who throws things away if they appear to be unused.