You may see the following error message when attempting to access a router's configuration page:
This article describes the cause of this problem and how to work around it.
Older routers will sometimes improperly regenerate their security certificates instead of keeping the same one for the life of the device. If you have added a permanent security exception for your router, and if this regeneration is done improperly, Firefox will detect the change as a possible attack.
The long term solution is to contact your hardware vendor and see if updates are available for your device which fix this problem.
If you are confident that no attack has occurred, you can work around the problem by deleting your old exception and using temporary exceptions for subsequent visits to the page:
To delete your old exception:
To add a temporary exception to allow access to the page:
The page will load.