|Seen this question a few times now.|
solution is difficult since these two devices are similiar except the mifi only allows wireless connections.
Only way I can see bridging these is to put a pc between the two and use ICS.
Pc would connect wirelessly to the mifi while also being connected wired to the airport.
You would need to configure the airport at a static ip in the ICS [9220.127.116.11 for host nic] range of 192.168.0.x. I would assign 192.168.0.254 to the airport for management.
Since the host nic acts as a dhcp server for the lan segment your lan devices would get ips with the proper gateway entry.
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