I recall visiting a website that said a PC logon password of 7 characters could be correctly guessed by some hacking equipment in as little as 2 seconds. I since increased it to 16 characters.
I know that logon password is relevant for home network....but is that also the case for someone hacking the router from outside ?
If you mean, can someone crack the router password.
In a standard setup, the router should not respond to attempts to access it's admin interface from outside, so the strength of password doesn't matter that much. This is normally the default setup. If however, remote access to the router admin is enabled then yes yoiu are relying on strength of the router password.
It quite normal to see all sorts of scans and probes in router logs, looking for open machines, or trying default passwords etc. But it's unlikely that anyone is going to bother trying to crack a router admin password anyway, they will jsut wait until they find an unprotected machine