I'm having this exact issue; I didn't try bridge mode because everything I have read said it has to be host, so I don't know if changing it would have fixed it for me and I'm not near the machine to try it now.
This is a brand new UnRaid setup and, if I remember correctly, bonding was on by default. However, I have only one NIC so I disabled bonding, and it shows as disabled in the setup. Not sure if it needs a reboot but maybe I'll try that as well.
I will be watching this thread for any further info.