Networking in lxc container

I am running an LXC container in an Ubuntu 20.04 VirtualBox virtual machine. I need to connect the lxc container to a bridge on my Ubuntu 20.04 host (I need to run the LXC container in a VM because of what I’m doing in the container). I setup virtualbox with two bridged interfaces to the bridge I need to connect to on the host. When the VM starts up, I can ping both interfaces from the host to the VM, and I can ping out of both interfaces from the VirtualBox VM to the host. I add one of these interfaces to the LXC container in the VirtualBox VM as a phys interface with the config below

Network configuration = phys = enp0s9 = eth0 = = up = 00:16:3e:5b:52:17

When I start the container with

sudo lxc-start u1

and I attach a shell to the container, I can see the interface eth0 with the ip from the config file. However, when I try to ping any interface, I get a ‘Destination Host Unreachable’ error. I also cannot see the LXC container on the network. Am I adding the phys interface incorrectly to the LXC container? Any help is appreciated, thanks!