Hi David Thanks for the guidance.
Felix, we usually ask operators of default bridges to configure these settings in torrc: AssumeReachable 1 Done.
BridgeRelay 1 Was already done.
ExtORPort auto I set my jail IP and port here.
In addition, it is best if you use a firewall to block the bridge's regular ORPort (while leaving the obfs4 port unblocked). Blocking the bridge's ORPort is a hack to prevent the bridge from being included in BridgeDB, which eliminates a couple of ways a censor might discover and block the bridge: 1) by enumerating BridgeDB, and 2) by fingerprinting plain-Tor connections to the bridge's IP address (made by users who discovered the plain-Tor port through BridgeDB). Done.
All is restarted and TBB obfs4 connects still fine. I have set up some Fallbacks of my own choise for the bridges. ok ? The bridges nat's to real guard IPs. A mid relay will never see the bridges IP. ok ? -- Cheers, Felix