I understand why this is confusing - the item model number indicated on Amazon is different from our site and it’s something they control. Anyway, here’s some clarity:
Anova Precision Cooker Nano 
#AN400-US00 serves 1-4
Anova Precision Cooker Wi-Fi #A3.2-120V-US serves up to 12
Anova Precision Cooker Bluetooth A2.2-120V-US Serves up to 8
The serving number really is just to give people an idea of how much they can possibly cook with the APC. It’s not a hard rule. Because really, a serving size can be subjective. Both models of the older APC can handle ~5 gallons of water just fine. However, if you have your water bath insulated and covered, the serving size can be much more than what’s indicated on the site. We have folks using large coolers with no problem - and that’s well over the recommended ~5 gallons/18.9 L. Seems like we have some discrepancies on the serving size on packaging vs. site. I will notify our team.