Does the vm have working network connection if the IP is set by hand, instead of DHCP? A question of whether the problem lies specifically with DHCP or with all traffic.
There are several threads on the VirtualBox forums discussing this, though not specifically with regard to E410 APs. Bridged mode is very often problematic on a wireless interface. Wired ethernet allows you to set promiscuous mode and will happily share the interface among multiple hosted VMs, but wireless normally doesn't support promiscuous mode, and wireless drivers (in the host system running virtualbox) frequently don't support vm usage so well. If you can dedicate an interface to the VM (even less likely with wifi than ethernet) you should be good, but the only solution may be putting the VMs into NAT mode.
I'm curious what you have set for "Client Isolation" and "Unicast DHCP" on the E410.
Has the VM host has been tested and confirmed working with any other wifi AP?
I would also ask the same question as Chanareddy's #2 - what is handing out the DHCP?
I'm far from a virtualbox guru, but I do have an ubuntu system (6-core AMD, 16gb RAM) that hosts cnMaestro on premises, a MySQL mirror server, and a third DNS server, so I do work with it regularly.
j