I am building (new setup) a relativley complex network with ER605 acting as the gateway to the WAN with three VLANs and managing DHCP on each Vlan.

I have the ER605 Linked to an T1600G-28TS smart switch with matching VLAN setup and Tagged ports etc on the trunk between them and all woks fine and devces on either smart switch Vlan port aquire their IP address from the ER606 fine and they in turn can see the internet but can not see devices on other Vlans as expected. 

I then added an EAP225 wireless access point to the T1600G switch on a port for the right Vlan and configued the AP for that Vlan with Tagged port on the switch which is itself conifured to use DHCP (as part of test process) and the ER605 is getting an IP address and I can access the AP Web interface fine (after looking up the IP address in the ER605 dhcp guest list) so I conclude that the AP is configured correctly and working with the other devics in the Vlan setup ok. 

However, if I try to connect to the AP wirless interface with an Android phone, the phone will not connect and I get unable to get IP address errors on the phone. If I "forget the network" and restart everything, the phone asks for the password for the right SSID (so clearly we are trying to talk to the right AP) but then fails to connect with the no IP error.

If however I configure the network interface on the android phone to use a static IP address it works so there seems to be a problem with the EAP225 working with an ER605 Dhcp server on android?   

Any thoughts as to how I go about diagnosing the cause please? 

Regards