Hi, is there a Max HDD size on Enigma2 STB's or is it dependant on the particular brand or model?

I see Andy_Hazza has a Vu+ Ultimo 4K with 3TB HDD, but most STB's seem to come with 500Gb or 1Tb installed. Is this a limitation or could I fit a larger HDD in most receivers? If so does anyone know max size - maybe it's limited to the old Windows 4Tb restriction??

Since OpenVix 5.4? there has been a requirement to give username and password, if this is left blank is there no password or is it root by default?
Reason for asking is that it used to be a lot easier to access the STB via windows and via my Lan, now I have to map the STB's drive with password to access, this also limits the drive being seen by other networked devices such as Android devices (Phones/Tablets).

Many thanks in anticipation.
Kevin