EVE-NG, Virtualbox, and Mac OSX: Can't communicate outside of the lab

Apologies in advance if this isn't the place to ask, but I figure this is where the most users of Eve-NG are going to be hanging out...

I am running Eve-NG on VirutalBox on my iMac running OSX Sierra. I have constant frustration getting the Cisco 3725/7206 to communicate outside of the virtual environment.

Virutalbox is bridging two LAN adaptors to either my wired or wireless connection on the iMac, depending on what I'm using at the time. I have an external network set up on EVE-NG that I bridge to either the Cloud0 or Cloud1 interfaces. (Both Cloud0 and Cloud1 are bridged to the local active network adaptor)

Initially, the emulated IOS images do not get an IP if I set an interface to get one from DHCP, but after some finagling (changing the adaptor that the external network is bridged to, restarting the router image, toggling the "cable connected" setting on the bridged adaptor in Virtualbox - I can get some communication working. In that I can get sometimes get a DHCP address, but I cannot ping the gateway (which is also the DHCP server). ARP entries show for the gateway on the router, but that's it. I can't get an ARP entry to show for any other hosts on the network if I ping from the router.

However - if I ping from the external network to the configured interface on the emulated router, I can get an ARP entry and ping replies on the host OS (i.e. pinging from OSX directly to the emulated router.) Even after OSX pings the device and an ARP entry is now in the router's ARP table, I can't ping from the router to the Mac.

It's driving me nuts and I'm hoping someone has run into this previously and can provide some advice.