It seems I need to seriously consider using real dhcpd instead of dnsmasq in dhcp-server mode since many have trouble getting an address from dnsmasq (it might not implement the protocol fully). However those that cannot get address via DHCP, please try manual address (start the backend via terminal to see the IP range it chooses) and report results (and if it doesn't work all the way to internet try pinging at least the N900)