Yes, the WAN port of a home router can be connected to the LAN (yellow) port of the V4.
Do take note the IP range of your home router does not coincide with that of the range of the gateway which the V4 will further connect to. There will still be internet access but no access to the devices on the same range.
For example if your home router range is 192.168.0.X and the V4 has a ZTE MF823 4G stick connected via the USB port, which by default is 126.96.36.199, your devices connected to the home router will have internet access, but will be unable to connect to the ZTE MF823 4G stick for configuration.
The EZhotspot Extender is a unique product that allows a smartphone or tablet to access it easily wirelessly for configuration. You never need a LAN cable with the EZhotspot Extender.
Even if you do need a LAN cable to connect additional devices, it is very likely the length you need is 3 meters and above and this cable is not able to fit into the standard box of the EZhotspot Extender and hence has to be ordered separately from your reseller , from our websop or easily purchased from any IT or accessory retail shop.