The firmware appears to have two bugs:
1. If I create two wireless networks, then I go to the Hotspot page and click Edit on the second network, then I select a profile (i.e. Cloud4Wi), the second network disappears from the Hotspot page and it is no longer accessible; requires factory reset to restore it.
2. If I enable Hotspot on a wireless network, then I add another wireless network without hotspot functionality, this result in the issue described above: DHCP works but no Internet connectivity
If I follow this order, it seems to work:
a. Configure first wireless network without encryption
b. Create second wireless network with encryption
c. Enable hotspot on first wireless network
With this sequence we obtain the desired result, hotspot on a wireless network and concurrently unrestricted Internet connectivity by connecting to the second network with its password.
There is a third bug in this case: QoS appear not working when connected to the hotspot, despite this is an officially supported device by Cloud4Wi and QoS is set in Cloud4Wi interface.