In our network we are using firewall to connect Branch to HO through site to site VPN .we using Controller as a DHCP -Server. Any option to flow DHCP for Branch user.
We are Using Identify V2110
AP-3705i
As that isn't clear from your post - are we talking about wireless users in the branch ?
If yes could you please post a screenshot of the bridge@controller topology.
if you are using a bridged@controller topology clients should get IP without a problem. If it's a bridged@AP topology you will need to configure a DHCP helper in your Client subnet.