Unfortunately many consumer and small-business routers come with insecure default configurations, have undocumented backdoor accounts, expose legacy services and have firmware that is riddled with basic flaws. Some of these problems can't be fixed by users, but there are many actions that can be taken to at least protect these devices from large-scale, automated attacks.
Don't let your router be a low-hanging fruit for hackers.
Basic actions
More complex stuff
Lucian Constantin