We have the same problem as well. I have spent 6hrs messing around with this today
Our setup is:
ETH0 - WAN
ETH1 - LAN with WIFI access points
ETH1.VLAN20 - WIFI ON VLAN20 - ADDRESSED -Private
ETH1.VLAN40 - WIFI ON VLAN40 - ADDRESSED + DHCP - Guest Internet access
ETH2 - PRIVATE NETWORK BRIDGED to VLAN20
The senario is that there is a private network SSID with vlan20 tagged on it. This is bridged to ETH2 and clients get their DHCP from the ETH2 network (not untangle)
Our guest wifi on VLAN40 (which isnt bridged) is working.
This was working fine before the upgrade. I can still reach the untangle box from the private network and can ping it from untangle. I have tried untagging a port on both VLAN40 (it works and i get the correct IP address) and VLAN20 (doesnt work) and connecting a laptop to make sure it wasnt the wifi.
Thanks
Jake