I'm writing here as to share some of my findings about hosting with Hetzner. All in one setups on single remote host can be tricky. Provider mounted an extra /29 subnet to the main host but none is routed by default and host has to become router itself. At the same time single mistake in bridging configuration and lost access results in need for re-bootstrap. It's still tempting to try and with many trials I eventually got to see guests talking to the net.

Scenario 1: Working. Package bridge-utils, oVirt engine, setup bridge, VDSM, add host to engine, add routing to host routing table. Networking by trial and error. Still something is not right. Occasionally on ping out I'm getting "Redirect Host (New nexthop" messages.

Scenario 2: Dreaming. Private network with private router/dhcp/nat. Private 10.0.0.0/24 network. No problems with routing as gateway 10.0.0.1 would be on the same subnet. Thought of using pfSense but can't seem to bring up an instance with two network cards on two different networks. I thought this would be easy. Go to Networks, click create new network, type private, save ok. then go to new instance. point at iso, attach two network cards. save ok. Launch "Host did not satisfy internal filter Network" No idea what that is. Maybe I don't understand how this works. I even tried removing ovirtmgmt network and leaving private network by itself. Tried with all 3 network card types (rtl8139/e1000/VirtIO)

Either way if you have a minute or two please take a look at both attached diagrams. Deliberately making it difficult by forcing all elements on single box in hosted environment. 

Maybe there is a way to have this all installed with Neutron or vSwitch on the same box or is that pushing it?

Regards,

Peter